Not sure if this will help! I used the potty party method with Jesse. It took a long time baby steps at first. But he was rewardedfor just sitting for a couple of seconds! Then when he came off we did a big production, dancing ( he loves to dance) and singing a made up song about him being a superstar......he also regressed after having surgery on his knee at 6. I stared all over again. It was hard but do not give up! He did it once and it made ur son proud! Getting over the fact that he associates pain with it will take a long time. Jesse would do the same, hold his poop for days. But we got there. I hope this helps.

My child's trouble was never quite so severe, however I can tell you that by eliminating the physical pain and then being as supportive as possible my daughter eventually gave up battling her own body about bathroom issues.
We set any expectation to use the toilet aside at one point and offered her diapers, or just go in your pants despite being a year potty trained, this seemed to help some. Mostly she was just scared of the pain and of losing control.
Eventually she worked it out with herself. It may have helped some that we repeatedly explained that the pain and uncertainty would go away if she let herself go everyday when her body "tells you it wants to".
Mostly looking back I think it was just something that she had to figure out with her own body and it took several months.
It must be so difficult for you, I hope that knowing this will pass eventually will help you now.

My son, now 31, would go for days without pooping when he was younger. He still doesn't go as often as a typical person, but has improved over time. I remember reading Jenny Maccarthy's book about her son with autism and that was the first time I came to know that bowel problems are common among people with autism. She also talked about the smell of BM's being much worse. I could totally relate to a lot of the things she talked about in her book. I also know that many parents, including her, have found that putting their child on a gluten-free diet helps a lot. I haven't changed my son's diet yet, but it may be worth it for you to check into it. It sounds like you are pretty stressed and rightfully so. I hope this helps.

We saw a big improvement with my DD and the potty training shortly after her biomed dr. started her on anti-yeast treatment with Nystatin. I was able to switch her to underpants during the day within a week of starting the Nystatin and (knock on wood) she has gone #2 on the potty at least once per day since with no accidents in her undies.

yayy crimson! That's awesome news!! My son will be seeing his ped. tmw. More blood in his stool :(