Hi - My Son Is 2.5 Year Old And From

Hi - My Son is 2.5 year old and from last 6 months very frequently he gets into a mode for a week where he gets watery lose motions, undigested particles & mucus was detected in stool test. He was admitted too couple of months ago for same reason and now again this month he is having motions. I gave him walamycin..

Please advise what is needed? or whats wrong?