My 10 month old is taking sulfamethoxazole-tmp for war ache. he won't eat had diarrhea and didn't sleep well at all. i don't know what to do ?

Needs re-eval: Smx/tmp is not the greatest drug for a middle ear infection. Many of the bacteria that cause middle ear infections are resistant to that antibiotic - at best, maybe 50% effective for ear infections. If child not improving, needs re-evaluation to see if the infection is clearing up. In meantime, can give pain meds to a 10 m/o, and sleep him upright in your lap as pressure greater when he lies down.