I also have had problems with gasey foods. Every time I have had to back pain (I also don't have a fill) it has been from gas that I can't seem to burp up. Beeno and Gas-x are my best friends.
I have been having problems with "gassy" foods, chili, beans, raw veggies, etc. I haven't had a fill yet but if I eat those types of foods I have problems.
Good Luck,
Jess