My son is now 3 and a half and refuses to use the toilet / potty. I constantly ask him does he need, he says no and then uses his pull up. I’ve tried just taking his pull up off but he just pees the floor! He doesn’t even tell me when he’s dirty and if I don’t change him straight away ( I have 2 other kids so could be a few minutes before I notice the smell) his bum breaks out in an awful rash to the extent it actually bleeds!! I’m lost for what to do with him as he’ll be starting school soon!! Help!!