Can SPD cause potty training to regress years later?

I have a nine year old who was diagnosed with SPD when he was two.

Recently, we are dealing with a new issue. He began about six months ago at the age of eight and half, having bowel movements in his pants again. He has been potty trained for four and half years. I read your article on potty training but it seemes to mostly focus on toddlers. Have you heard of older children with SPD that can regress due to lack of sensory signals in that area?

He doesn't seem to know that he has had a bowel movement or when he needs to have one. He hasn't been in OT since he was three because the insurance didn't feel he needed it. But some of his problems have seemed to worsen.

He also makes a lot of of constant noises with his mouth and can't seem to control it. He is very aggressive with his siblings as well. I want to arm myself with information so I can ask his pediatrician what to do.