Hi my son is 4 years old, He developed a temperature 39.8c, 2 days ago out of the blue, I can seem to get below 37.6-37.9 before it back up again, he has been sick a couple of times off his food, but very thirsty, took him the hospital, and was told he has a chest & throat infection, this morning I noticed some small flat red spots on him and now seem to be more, what do u think it could be? should I take him back to the hospital, (he is taking antibiotics)