Andrew,
It sounds more like an inflammatory bowel issue. Since you've always had IBS, if you're not willing to accept that, see a GI doc about doing a work-up for Crohn's or ulcerative colitis. You could also ask to have your gallbladder examined further.
The roast may have just caused excess gas. I'm sure that's where a lot of my RUQ pain comes from since everything has always checked out normal.
All your liver values are normal (except very slight increase in bili which could be Gilbert's phenomenon - a benign issue)...I'd focus on gut for now.