hi all, my son 9 mths old having diarrhea past 1 week

hi all, my son 9 mths old having diarrhea past 1 week. We took him to clinic yet do not know the reason.Requested to change milk to soy based powder( and avoided all the dairy products) in a day he is going 10 times but little amount. i am really worried! anyone can advise or share if u experience this before? any docs here?