Please help. 6 year old still poops his pants

From the wiggle it's usually apparent to everyone on the room that he's
pooping his pants except him. Other times he'll come in the room with poop
on his hand crying. See, he checks himself and appears to be surprised when
he finds something there. Every time he does find something he bursts into
tears because he knows we're going to take away TV privilages or something.
We really don't know why he does it, and we're really tired with the whole
issue. The boy is six years old now. When he does go, he generally has
disturbingly large bowels - larger than that of your average adult (I guess
I'm about average). The doctor has us giving him laxatives every day
because he holds it in otherwise. I don't know what to say to him after
each episode except that I'm extremely disappointed... We don't know if
he's really aware of it or not, but I can't imagine how he wouldn't be. Has
anyone any experience with something similar? The kid is also skin and
bones and I"m afraid that the daily laxative is keeping him from getting the
nutrition that he needs to grow.

Thanks, Steve