Welcome to the gastroenterology community! I agree with Sherah that you need to find a doctor that will listen to you. Also, I don't really agree with the medications your doctor has you on. I am not a doctor and it is only my opinion but I don't recommend that anyone with possible intestinal problems take Norco as this can cause a lot more problems. Also, I believe the levbid should only be used on an occasional as needed basis, and the symptoms you describe don't really sound like they would be helped by Levbid. If you are worried about IBD, you should talk to your doctor about getting a colonoscopy. Good luck.
It could be many things and I've been thru the same issues as you only dealt with it my whole life up until just recently. My issues have to do with my gall bladder and getting a doc to listen without just giving some mental drug or other drugs that don't work is very difficult. They tried to give me antidepressants and I had a fit in the doc office, then they wanted to set me up an appt. with their mental health dept. to "learn" how to deal with my anger, LOL. I'm so sick of heartless, ignorant doctors! Do your OWN research and try to find a new doc that might listen and run more tests. My gall bladder tests are showing nothing (they are very flawed) but due to my autoimmune disorder, they're going to take it out anyway based on symptoms, family history, etc. It took me years to get this accomplished and several doctors to find one that would even listen to me. Might want to look into Chron's, celiacs, or even the side effects of the meds your on, that's a big possibility. Some of the meds, like the ones your taking, might affect stomach and intestinal motility.