Viral exanthem rash on toddler

My baby was diagnosed with viral exanthem rash on his body and it keeps coming back. Is that what it does? It will mostly go away then come back again. It's been at least 2 months that he's had this. I don't want to look dumb going to the doctor for the same rash on him. He's so itchy my poor baby. I give him Benadryl every 6 hours but doesn't help much...