I have a 3.5 yr old son and a 2 yr old son. Their father and I broke up 7 months ago and I recently moved in with another guy. He has 2 boys of his own - same ages. My 3.5 yr old has recently started going to the bathroom in his pants. He has been potty trained for some time and has had occasional accidents, but for the last week he has not had a bm on the toilet once - he goes in his pants. He does urinate in the toilet though. I want to know if he's regressing to get some attention because there are 4 kids in the house now, if he's doing this because he misses his father, or if there is some medical reason.