What Causes Rashes On Legs And Itchy Bumps On Ankle?

I recently came down with what appeared to be some sort of rash all over my legs- hives, maybe? Hundreds of itchy bumps from hip to ankle. After a few days i went to a doctor and received a steroid shot. When that didn t help, i tried Benadryl. Im not sure if that worked or if the mystery ailment just finally ran its course- but it cleared after about 6 days. Its a week later and I still have dark marks all over my legs from where each and every bump was. Will these fade?