My son is 3 years old. He is currently pee pee trained. I am having trouble with pooping. He had no problem in the beginning with him sitting on the toilet. He actually started peeing that way. He has never gone poop in the toilet but now he won't even sit on the toilet. He will show that he needs to go but will scream if you try to sit him on the toilet. He will actually suppress it till night time when I put the pull up on at bedtime and 5 minutes later I have to change him. He went from 3 to 4 times a day to maybe once a day. They have gotten hard because he is holding them back. Does anyone have any suggestions to get him to go in the toilet? Possible health issues are starting to concern me.