Rash?

I have this rash, this picture is the best I could get and it isn't a picture of it at a point where is is really flared up. It is kind of bumpy, not scally, just bumpy almost like how poison ivy is kind of raised up. It itches, but when I scratch it it burns, and just gets even more red. I called a nurse at our local hospital and they said to take Benadryl and use hydrocortisone cream. Has anyone else gotten this? I forgot to mention it extends from my wrist to the top of my shoulder by my neck, but is worse on my left arm than my right.