My story is very similar to Mari's (started with chronic diarrhea and stomach issues), along with occasional achiness all over.
Fast forward to 2011 when I developed gastritis after surgery---major stomach pain! I thought I was having a heart attack when those pains came.
I don't know if this will help anyone here, but for my gastritis I took licorice (DGL chewable licorice extract tablets--Puritan has them) and also a little aloe gel in water, daily. Again, this was for gastritis, so it may not help everyone, but it sure helped my stomach to heal.
Some cautions: Check with your doctor before you start anything, including anything herbal or even the aloe gel, as some people don't tolerate it well at all. Plus, the aloe gel can be laxative for some people. And obviously, there can be bad interactions with meds you are currently taking.
Personally, I think IBS can be almost as tricky as fibromyalgia! Diet 'do's' and 'don'ts' are found by trial and error and seem very individualistic.
Good luck and I hope you find some relief soon.