I had a toothache for the past two days. I had a toothache for the past two days.

If you are no longer in pain, then "I had" is correct. If you are still feeling pain when you are writing the post, then "I have had / I've had" is correct. I mention this because I don't know if "in the trenches" means you are still in pain.

It hurt me all night and it was so hard to bear it sothat I went to the hospital early in the morning. It hurt all night and was so hard to bear that I went to the hospital early in the morning.

It hurt me all night and it was so hard to bear it so, I went to the hospital early in the morning. It hurt me all night and it was so hard to bear, I went to the hospital early in the morning.

I would probably say "it was so painful, I went to...", but this makes sense.

It hurt me all night and it was so hard to bear it sothat I went to the hospital early in the morning. It hurt me all night and was so hard to bear that I went to the hospital early in the morning.

It hurt me all night, and it was so hard to bear it, so I went to the hospital early in the morning. It hurt me all night, and it was so hard to bear it, so I went to the hospital early in the morning.

So, here is the comma grammar: your sentence has three parts. Each part is an independent clause. They each have a subject and a verb, so they could stand alone as sentences (if they started with a capital letter and ended with a period). Independent clauses should be separated by a comma or a semicolon (;). I think of a semicolon as half comma and half period. It can only be placed in the middle of a sentence, and if there are a lot of commas, it is useful to show a bigger separation between clauses. One way to punctuate your sentence with a semicolon would be: "It hurt me all night, and it was so hard to bear it; so I went to the hospital early in the morning." The first two clauses are about the toothache; the third clause is about the hospital. However, this is an awkward sentence because it repeats the word "it" three times and the word "so" twice. Here are two other ways to write the sentence that have fewer commas: "It hurt me unbearably all night, so I went to the hospital early in the morning." "It hurt me all night, and it was so unbearable that I went to the hospital early in the morning."

The dentist said that my toothache was terrible, and it needed a long time to treat, and I should go to the hospital three or four times over half a year. The dentist said that my toothache was terrible, it needed a long time to treat, and I should go to the hospital three or four times over half a year.

While "hospital" is technically fine, I assume you meant "dentist". Usually I say "the dentist" to refer both to the dentist himself as well as the physical location. Also "dentist's office"

The dentist said that my toothache was terriblin bad shape, and it needed a long time to treat, andso I shwould need to go to the hospital three or four times over half a year. The dentist said that my tooth was in bad shape, and it needed a long time to treat, so I would need to go to the hospital three or four times over half a year.

The toothache is specifically the pain you're having. The dentist wouldn't know how bad the pain is, but they would say what was causing it and how bad *that* is.

The dentist said that my toothache was terrible, and it neededwould take a long time to treat, and I should go to the hospital three or four times over half a year. The dentist said that my tooth was terrible, and it would take a long time to treat, and I should go to the hospital three or four times over half a year.

The dentist said that my toothache was terrible, and: it needed a long time to treat, and I should go to the hospital three or four times over half a year.the next six months. The dentist said that my toothache was terrible: it needed a long time to treat, and I should go to the hospital three or four times over the next six months.

Here I used a colon. This means that the second two independent clauses explain the first clause. We usually state time in months rather than fractions of a year.

She also told me to take medicine three times a day and not to eat spicy foods. She also told me to take medicine three times a day and not to eat spicy foods.

I think "not to" is fine but I'd say "to not".

She also told me to take medicine three times a day and not to eat spicy foods. She also told me to take medicine three times a day and not to eat spicy foods.

I think "to not eat spicy food" is a bit more clear here, but this is fine.

It's really a bad news to me, because I love spicy foods so much. It's really bad news to me, because I love spicy foods so much.

IThat's really a bad news tofor me, because I love spicy foods so much. That's really bad news for me, because I love spicy food so much.

Original was mostly fine, but this is a more natural way to say this.

It's really a bad news to me, because I love spicy foods so much. It's really bad news to me, because I love spicy foods so much.

“News” is uncountable, so we say “it was bad news” instead of “it was A bad news.”

IThat's really a bad news to me, because I love spicy foods so much. That's really bad news to me, because I love spicy foods so much.

"That" is a more specific way to refer back to what the dentist said, and it sounds more natural to me.

As expected, I will be in the trenches in the followingnext few days. As expected, I will be in the trenches in the next few days.

It's difficult to explain why I think "in the next few days" is better than "in the following days." One reason is that "the next few" definitely refers to the future. You could also say "in the upcoming days" or "in the days ahead" to refer to the future. "In the following days" can also mean the days after something. Maybe you used it because the days are after the visit to the dentist--but since the main verb "will be" is in the future tense, I think any of the other expressions are a better match. Note: if you want to avoid using "in" twice in the sentence, you could say, "for the next few days." However, "for" does not work well with the other two phrases I suggested.