My 3 1/2 year old son won't stop pooping in his pants

[Mommyof2snbiabc]

My son is almost four years old and has was COMPLETELY potty trained by the age of 3. But about a month before my daughter was born he started pooping in his pants. at first it was only once or twice every week or two but after my daughter was born he poops in his pants 3-4 times a day. sometimes it's just small like maybe a 'wet' fart other times its chunks in his underwear and, again, other times he FILLS his underwear to the point were i just put them in a bag and throw them away. I don't know if it's an attention thing or what...i don't really think it's attention because i still live with my parents and he's always been closer to my mom then me and he gets plenty of attention from both of them and from me so i have no idea what could be wrong. his diet is fine. I am about to have a breakdown over this and have no idea what to do. I feel like i've tried everything.

[AdinaL]

Is he having any constipation issues?  This is the only time my daughter had issues with accidents. And once we resolved her constipation issues, they stopped.  If you search the board for encopresis or constipation, you might find some options.  When I looked I found that it seemed really common between 4 & 5 years old to have some sort of digestive issue.

[Youngfrankenstein]

We struggled with this with both of our boys until about 3rd grade.  I hear from so many mom's that it can be this way.  It was annoying as hell and we tried talking and punishing but it just was the way it was.  I just think they couldn't mentally connect the dots.  I don't even think they realize it sometimes.  And you couple that with the times they were just being lazy and it lead to a lot of stinky laundry for me, for years.  My dd has never had the problem.