I've been havinghad the flu for a few days. I've had the flu for a few days.

I've been havinghad the flu for a few days. I've had the flu for a few days.

Alternative: I've been sick with the flu for a few days.

I've been havingsick with the flu for athe past few days. I've been sick with the flu for the past few days.

Slightly better rephrasing.

Last Wednesday, I felt a little undiscomfortable in my throat, but it wasn't unbearable. Last Wednesday, I felt a little discomfort in my throat, but it wasn't unbearable.

"Discomfort" is used over "uncomfortable" in the context of symptoms/pain

Last Wednesday, Imy throat felt a lbittle uncomfortable in my throat sore, but it wasn't unbearable. Last Wednesday, my throat felt a bit sore, but it wasn't unbearable.

Things went worse on Saturday after I got back from a hike and my period came. Things went worse on Saturday after I got back from a hike and my period came.

"Things got worse" sounds more natural to me, but I guess "went" isn't exactly wrong.

Things wengot worse on Saturday after I got back from a hike and my period camestarted. Things got worse on Saturday after I got back from a hike and my period started.

More natural

Things wengot worse on Saturday, after I got back from a hike, and my period came. Things got worse on Saturday, after I got back from a hike, and my period came.

Things went worse on Saturday after I got back from a hike, and my period came. Things went worse on Saturday after I got back from a hike, and my period came.

I woke up with a blockstuffed nose on Sunday (morning), and stayedwas dizzy all day. I woke up with a stuffed nose on Sunday (morning), and was dizzy all day.

I would omit "morning" since it is assumed by the reader by "woke up"

I woke up with a blockedstuffy nose on Sunday morning, and stayedwas dizzy allthe whole day. I woke up with a stuffy nose on Sunday morning, and was dizzy the whole day.

I woke up with a blocked nose on Sunday morning, and stayedfelt dizzy all day. I woke up with a blocked nose on Sunday morning, and felt dizzy all day.

Yesterday, my nose was blocked first, and then it flowedran. Yesterday, my nose was blocked first, and then it ran.

Also "stuffed nose" is more common in my American dialect at least, but "blocked" is okay too.

Yesterday, first my nose was blocked firststuffed, and then it flowedwas runny. Yesterday, first my nose was stuffed, and then it was runny.

The symptom terminology is typically stuffed nose and runny nose

Yesterday, my nose was bclockedgged at first, and then ithe mucus eventually flowed out. Yesterday, my nose was clogged at first, and then the mucus eventually flowed out.

I had to work from home to avoid interrupgetting others people sick. I had to work from home to avoid getting other people sick.

Flu during thea seasonal change is so terrible, that I hope you all are goodre all feeling well and healthy. Flu during a seasonal change is so terrible, that I hope you are all feeling well and healthy.