rash=rheumatic fever or related to strep

My six year old daughter has had a rash since september, two weeks after I noticed it, she had a sore throat and was diagnosed and treated for strep. The Dr. said when the rash was still there weeks later that it could be strep related and it would run its course and to keep him posted. Now wants to refer to dermatologist for possible allergies. I am wondering if my instincts are right and that it is not allergies but caused by strep virus. The rash does not always appear, it comes and goes throughout the day and resembles hives and pink blotches. Will a dermatologist be able to help if it is NOT allergies and is strep related?