<s>[INST] My 13 month old son has been passing very runny, milky yellow poos that smell very bad and fishy?! I was unsure if it may have something to do with him now being completely weaned on to cows milk but he s had it one way or another since he was 6 months old and this is the first time there has been an issue. He s not poorly on himself and isn t off his food, he drinks plenty throughout the day. Any advice before I go to my GP? [/INST] Hi,Thanks and welcome to HCM .Your history suggests that he may be suffering from giardiasis .Metronidazole is the drug of choice given 2times daily for 3 days.Normally the motions will become normal.you may ask for stool examination for confirmation of diagnosis.I f no improvement consult pediatrician.Hope this answer is OK for you.Please feel free to ask further queer if any.Dr.M.V.Subrahmanyam. </s>