Hi and welcome,
The first thing is wait for the biopsy, but sounds as though the Doc is leaning towards Crohn's. Crohn's and ulcerative colitis look very similar on colonoscopy. The only real difference is the depth of the "ulcer". I have Crohn's in my large left intestine which is a less commom place for Crohn's and more common for Ulcerative Colitis, but after biopsy....it was ruled definitely Crohns.
I would say that definitely all of the NSAIDS that your husband is on could definitely cause complications, just not sure it would be in the large intestine without being in the stomach and small bowel first. One thing I have learned thru all of this is that Anything is possible. Once there is a definitive diagnosis, his GI will address all the meds that your husband takes, and would more than likely have him stop all NSAIDS.
The rectal muscle pain is common in both Crohn's and UC (ulcerative colitis).
The very most important advice I can give you is to definitely develop a relationship with his GI doc and MAKE your husband go to the GI reguarly, keep appts etc.
Good luck, stay in touch with the forum so when can know how he is doing.