I gave my son a bath in the morning and noticed maybe one or two red spots, which I thought might be mosquito bites, by the time I changed him into play clothes 3 hours later, he was covered (trunk & extremities) with red spots. He didn't really act sick and there was no sign of a fever, I thought it was an allergic reaction to something. By that night, he started to develop a fever and the red spots had grown in size and number, some of them were combining together to make one big red area. That night he was very uncomfortable from the fever and itching. This morning he still is hot with fever, and his red spots are raised circular looking with white skin in the middle. I've checked just about every common rashes symptoms and have found nothing that matches his exactly. He has them on his face, forehead, ears, arms, legs, trunk, and it was on his neck last night, but doesn't seem to be now. Should I take him to get checked, or let it run it's course? What should I be watching for?

Optional Information:
Male , Age: 2

Already Tried:
Hydrocortizone cream, Benadryl, and TYLENOL