I too thought it was pelvic floor contraction because his symptoms sounded like what I had, it’s so misleading because the pain is more in the rectal area and sometimes in the pelvic region. I was given a drug called Amitriptyline which is actually an older antidepressant, I started on 5 mg. for one week and then 10 mg., it took all the pain away, it’s curious to me how this drug did stop the pain but I’m very happy it did. I think that it might be worth trying this medication or something similar and see if it works for him, I sincerely hope he gets relief because chronic pain is definitely awful, best wishes.