my baby is 6 weeks old. he started off with normal stools which were bright yellow, then he got thrush and was prescribed nystatin which he had for 2 weeks. During this time his stools changed from yellow to a horrible grey clay colour and VERY smelly. I thought it might be something to do with the nystatin, but he has now been off this for 2 weeks and still the same grey clay-like stools. I have asked a doctor and they dismissed it as oh it sounds like a little tummy bug, babies can get tummy bugs very easily, dont worry but he has had this for over three weeks now? Should i be worried? should I go to the doctor again?