My 12 Year Old Grandson Has Problems With Bowel Movements.

My 12 year old grandson has problems with bowel movements. His stool appears soft and smells much worse than normal. He leaves a very strong odor down the hall. He uses a lot of toilet paper with every bowel movement. He fills the toilet with paper and clogs it every time he goes. This doesn’t seem normal to me. When he was 10 years old he was pooping in his pants. I would like to know what a normal bowel movement should be like for a 12 year old.