I ve been taking an antibiotic for a cat bite for 9 days. A week ago I had a small patch of poison oak on my wrist . ( I m allergic to it.) about 3 days ago, I felt ( what I thought) another patch of poison oak on my back. I washed all bedding,towel, and clothes, yet felt it spreading to chest , belly and genitals. It felt like PO in every way, yet when I felt the tops of my feet begin to itch, I wonder it s an allergic reaction to antibiotic. Is it possible to develop a reaction so many days after taking it? My Dr. Said I could stop using it after 10 days if all was well. The bit is fine. I began using prednisone today.