hey moms so about 3 days ago my son had a fever that reached 102. took him to the er and it was…

hey moms so about 3 days ago my son had a fever that reached 102. took him to the er and it was nothing serious, they chalked it up as being a "cold". it finally went away yesturday. while me him and my mom were out and about yesturday he was exposed to direct sunlight for longer than i usually like him to be in. then my mom fed him a tiny bite of an apricot cookie. as we are going home i notice tiny red bumps on his face, neck and chest but then by the time we got home and got comfortable they were gone. so at that point i was like "meeh was probably a slight heat rash". so then this morning i wake up and he is entirely covered. they still havent gone away. but as i was keeping an eye on it, it seemed to only get worse while he was exposed to the sun. but im leaning more towards a food allergy. what do you ladies think? id like to know some opinions before i go to the er again tomorrow. thanks in advance!