@Pandora I assume you are talking about a zpack when you say 5 days of antibiotics. That drug has a long half life and lasts in the body longer than say penicillin like Pen VK, or Amoxicillin. It is actually working for several days past your last pill. Trouble is it only works if it is the right drug and the right dose, like any other antibiotic. You probably wound up eventually on something Levoxin, or maybe just good old Augmentin. My guess is none of the doctors, even the one who gave you the better drug, did a culture. Right? They just guess. They just guess and prescribe what they always prescribe.
Possibly you had some other low level infection for a long time, and that is why the 5 day drug worked on your worst sympoms, but the other magical pill worked on other crap in your body.
My advice is really start to learn the medications that work well for you and in what doses. Of course with each bacterial infection it needs a specific med, but you can start to recognize the symptoms of each illness and what drug you prefer. You might not get sick like that again for 5 years.
And, @gondwanalon is right it wasn’t a virus, it was a bacterial infection.
@Jude A flu shot might be worth considering since you are getting sick a lot. You have probably seen me on other Q’s, I don’t get the shot myself, but I would definitely consider if I felt I was at more risk of catching the flu, or becoming very ill from it. Just know that the fou shot only works for the flu. It will not help with colds or bacterial infections.
I also think @JilltheTooth made a really good point, you have been through a very stressful time. Do what you can to pamper yourself. Most of all get plenty of sleep. I get sick a lot when my iron is low, maybe check that next time you are at the doctors office.