3 year old son, prescribed this med, due to possible allergic rea...

3 year old son, prescribed this med, due to possible allergic reaction last spring, with Amoxicilian, for a sinus infection, this year for ear infection. Took his last dose today, of 10 doses, began with a temp, yesterday of 102.4 (spike), and noticing, daily, cheeks getting progressively red, today the worst and still fever. Looks like an allergic reaction also, and I'm seeing the beginning signs of small red dots on his trunk, also increased urination, with hot and cold sweats. I'm hoping this clears up now that he's finished the Sulphameth, another red alert.