6 month old pooping continuously

Tara
For over a week now my 6 month old has been pooping several times a day. Literally every diaper change there is poop in his diaper. I find myself changing one diaper then minutes later changing him again. He has a bad diaper rash because he has been pooping so much. I've taken him to a doctor and they gave him burn cream for his butt and said that there was nothing they could do about his constant diarrhea. Is this happening to anyone else? What can I do? I try feeding him certain things to stop it like bananas but nothing's working.