S.M.
I have had this problem and my son started to use the potty then because he told me when he had to go. One question I have for you is "can he tell you when he goes in his diaper?" If so, then I is time to maybe try to potty break him. If not, Then all I can tell you is to watch the amount of liquids that you give him. If this doesn't help and you can't find any other way to deal with it then I would talk to his doctor because he might have a blatter problem. Well I hope this helps and if not then I hope you find a solution for it.