Could Red, Raised Spots On Body Of An Infant Be Newborn Rashes?

Dear Doc, my baby boy is almost 7 weeks old. He has had a rash for the last 6 weeks now. It began on his cheeks and spread all over his face, into his hair, down his neck and chest and now it is on his arms. All the doctors and nurses I have seen have said it is a newborn rash, which wiil resolve itself in time. I think it seems a little too persistent to be a newborn rash, coupled withh the fact hat some days it appears better and then it gets worse again. Iit is very fine on his chest, but quite red and irritated on his chest and face.It looks like slightly raised red spots, all joining together. What is your opinion? Newboen rash, or something else like an allergy?