One supplement that will "feed" your gut is L-glutamine. It won't cure your FBO, but will aid your intestines. Take the PURE powder (at healthfood stores) and it'll be a fine powder and mix 2 grams (using scooper in jar) in water on an empty stomach every day. Slowly move up to a higher amount if your system is okay with that.
For some reason, I can only handle the 2 grams per day. . .
A jar is around $20 and will last probably six months if you do the lower amount.