After antifungals, I developed pretty bad SIBO, pretty quickly. The effects of Hydrogen Sulfide were the worst symptoms (CFS/headaches), but I also had some bloating and indigestion.
I treated with high dose Vitamin C (per Dr. Myhill) in addition to HCL and enzymes. I kept it away with bile salts and whey protein.
I've never tried Castor oil, but it's worth a try. It's laxative and anti-inflammatory effects should be helpful.
Unfortunately, bloating and indigestion can also be caused by an intolerance, so if you try these sorts of things and still have symptoms, that may be an avenue of exploration.