Red Spot On Ankle, Large Welts Spreading Over Feet, Legs, Hands. Treated With Steroids, Recurring On Elbows. Treatment?

I had a round spot on my ankle over a year ago that started out as small little bumps an became large welts it started to spread all over my feet as small bumps and got larger my doctor thought it was poison an ivy and treated it for that. it cleared up with the steroids but after i stop the the treatment it came back. after several treatmenst and several months later it went away. a few months later it came back on my elbows. now almost a year later it is starting to come back. I must mention that it is only on my feet legs hands and arms. can you help me figure out what this is?