From my experience recently (with a grandson), it could be constipation and/or family changes. A grandson almost 5 yrs. old became constipated and finally they were told to give him a suppository. Not a good idea as he then quit going until he couldn't hold it and went in his pants. Also they have babies and they get attention and are a lot of work and he was the only one for so long. I think both of these things played a part as he got more attention plus was afraid of it hurting or having anything else done. It took along time and he'd get worse as it went along in time and then started yelling when made to sit on the stool. I do believe that was for attention. If I said stop now he did so pain is not that easy to stop. He is back to normal now pretty much but he still does have some issues with constipation. What is causing all these constipation problems in kids and babies these days? I know of many babies on things for that and never heard of so many issues with that years ago. Anyhow, be firm, try to figure out if it's pain, fear, attention or what and then be patient. I know this is very hard to deal with.