Does this wasp sting sound normal?

I got stung over a week ago. The first day I had a 2 inch blotch. The second day my entire leg was swollen, bright red and hot (12 inch radius) and I had a terrible migraine with nausea and dizziness. The 5th day, the swelling moved down to my ankle, and my leg was still splotched over a 12 inch area. I ended up going to the hospital because I was also getting nauseous again and I felt like maybe I should have someone look at it to make sure the circulation was okay. I had already tried taking benadryl, applying cortisone and taking advil.

The ER doctor said that I "may" have cellulitis and strongly suggested that I take a full course of Keflex. I was hesitant at first since he wasn't positive, but it flared up again with burning and itching and I was also getting really tired and had joint pain on day 6 so I took it. Now I've taken the keflex for almost two days and I still have the swollen ankle and splotch. I'm also tired and have a stomach ache and may have a slight fever.

What should I do now? Should I continue to take the keflex? It doesn't seem to be helping.