What Causes Itching Red Rash After Urticaria Treatment?

I had flu with a sore throat about 6 weeks ago. Since then I have developed urticaria which resolves with antihistimines but I have also developed a rash that seems to migrate, redness, swelling and some itching.I also develope bright red sollen areas that resolve within 48 hours to reappear somewhere else. I have seen my GP numerous times, at first she thought it was gout, but I had a normal uric acid level, my liver functions are fine, kidneys fine, no rheumotoid factors detected, no diabetes, no anemia. Because the itch and rash (urticaria) was worse at night scabies was also considered, I used scabies treatment creams 3 times, two different products. The red patches seem now to be more on the back of my heel and the arches of my feet. Occasionally my feet swell with the redness. Any suggestions?