Suggest Cure For Heat Rash

15 mo. old son in otherwise fairly good health ( just finished 10 days amoxicillin for an ear infection) seen for check up just at the end of nov. has red spots on face back chest and arms, acting out of character so we went to the doc. of course i was made to feel like an idiot because my son was not displaying the symptoms at that specific time ears nose throat all good reflexes all good. . we inquired about the few spots at first (not as many were apparent to him at first)...doc yesterday said it was heat rash... i completely tried to control the cliamate all day ... and now theres more? he goes from happy and healthy to a miserable episode where he screeches and looks like he is in pain or discomfort ... puts his head down blinks slowly and just looks like it feels horrid....i'll calm him down then back o happy... rinse and repeatt every few hours. been goin on for over 48 hours now . what to do?