My 6 year old son is having accidents during the night & during the day?

[Deb4christ]

My 6 years old son is having accidents during the day.  He rushes to the bathroom to go poop or at times will pee his pants (rarely pee his pants).  We've had more problems with him pooping in his pant (usually he has a smear on his underwear and is rushing to go poop 8 -10x a day).  He pees during the night in his bed, so he is in goodnight(pull-up) during the night.  We eat healthy,whole wheat, oatmeal, plenty of veggies & fruits and drink water.  There was a very traumatizing situation that occurred when he was 4 years old with the toilet.  My in-law's toilet was plugged up and my Father in law was positive that my son put a toy down the toilet. My father in law said his toilet has never plugged up.  As it turned out my husband plugged up the toilet and he forgot about it.  My son went into the bathroom, after his Dad plugged it up, to go and then flushed and the toilet started to rise.  I think with seeing the toilet being plugged and hearing his Grandpa accuse him of plugging it up my son was traumatized by the accusation.   I believe my son doesn't relax to go potty because of the fear of plugging it up.  What do you suggest we do to alleviate this fear?  We are sitting with him and reading books to him so he can relax and we going every 30 minutes.  I just started this yesterday but he still had poop in his pants.  Any other suggestions would be greatly appreciated.  Thank you.