@glenntaj
Thanks a lot glenntaj for the advice. Yes, I should get more thorough work-up. And no, I don't have access to my MRI's and CT's etc. And thanks for the links.

@kiwi33
No, thankfully it does not seem to be FAP. (Which I've also, thankfully, had not heard about, or I'd be really scared before I knew.)

@Healthgirl
Great advice. Thanks! And sorry to hear about your condition. And yes, it's quite possibly some sort of autoimmune respons. I tested negative for Celiac back when my daughter was first diagnosed. But has not tested for anything else autoimmune-related.
And I will definitely be careful with the alcohol, thanks. I've even stopped taking the anti-inflammatory pills when the back pain flares up.