Constant wetting

My 4 yer old constantly setting himself and I mean to the point where he is dripping in even limiting his drinking to sips , he wears normal pants in day and bedtime pants in night he speaks through the bedtime pants I usually change him abou 3 times in the night , he seems to be constantly wet even when he hasn’t has a drink . 

Please help sorry i have put so many threads up I just at a point where I’m breaking .