I Had The Flu Last Week And Was Given Tamiflu.

I had the flu last week and was given Tamiflu. That then became a sinus infection treated by an antibiotic. I do feel somewhat better however I now have pain in my lower back predominantly on the left side but also on the right. Not sure if I am now dealing with a kidney infection. I have RA and take methotrexate ( weekly) and 2.5mg of Prednisone along with Folic Acid ( daily)