K.:
I know it's funny (not ha-ha) but stomach pain is one of the signs of strep throat.
He should have been given an antibiotic for the strep. If his stomach is STILL hard after taking the antibiotic? Try yogurt.
If his bowel movements are hard - do NOT give him bananas this will only make it harder. Usually with an antibiotic one gets diarrhea because the antibiotic kills all the good bacteria too...therefore yogurt is usually a great balance!
If he is having trouble going? I would be concerned since he's on an antibiotic and would call the doctor. I'm not sure what you are giving him to help him go - but warm maple syrup and peanut butter are WONDERFUL natural laxatives....