Rash on 6 month old back

My 6 month old daughter has had a rash on her back that comes and goes for 3 days. We started her on purées and I noticed the rash that night. Idk if it was there before we introduced food or not to be honest. She has only tried sweet potatoes so far. I took her to the pediatrician and he said it doesn’t look like hives so he’s not concerned but it continues to come and go. Anyone experienced similar? Most of the red splotches are flat but a couple of them feel similar to a bug bite.