Your story is interesting and nothing which I've quite read before. Is the rotten teeth due to any meth use or other drugs? I would stop all except there is some folks who have said pot alleviates symptoms and makes them feel better (it's illegal for me here and at my work).
poop which looks like coffee grinds, says this website
Go Here implies bleeding in the upper GI where the blood is processed by stomach or upper GI acids. You can search more on that.
You need to get yourself into as consistent a routine as possible. Sleep, eat, medication and some light exercise even if its walking around. Stability allows you to tells what made something happen; your body will better tell you what's wrong.
Buy a small whole chicken and carrots, celery and onion and make some soup. Boil until it's falling off the bones and scoop it out and pull the meat off and add some egg noodles and that can be your base food. After a few days eating that just add certain foods and see what you can tolerate. Keep a journal of what makes you feel worse or better. This help many.
When in a bad flare I can't eat anything without pain but this broth might at least provide you some benefit over what trash (ice cream) you've been eating.
Pain - I used to get a wet washcloth to bite if I couldn't scream (as in not wanting to put fear in my wife and kids). Screaming will help as will biting into a towel. The worst that will occur is you'll pass out from too much. I often got light headed and threw up due to pain.
This is a painful disease and your body has it's own way of dealing with pain. The pain meds you previously took make you more sensitive to pain so you're best to avoid pain medication and begin training your body to produce its own endorphin response.
Hope you start learning some answers soon