I agree with the gallbladder thought, the gas I think is pretty normal. In general gas smells depend on what you’re eating. But for GBS patients I believe it has more to do with an over production of bacteria in the gut. I would be more concerned about the color of the stool that can be an indicator of a few different things. Considering that having this surgery has the possibility of putting your gallbladder in a tailspin I would definitely have that looked into. If your bypass doctors are not acknowledging your concerns I would def go to your primary or another GI doc. I started having a shlew of GI issues about 2 yrs post op (which i had 0 of before) and after asking my bypass doc he was very dismissive. I’m assuming because their not performing this surgery anymore where Im from they don’t want to be associated with any problems when it comes to the GI and the other issues ppl are having years down the line. So best to have that addressed even though it may not be serious it would be good to look into it. Also because of the malabsorption we already face from having the surgery, having chronic loose stools or diarrhea is something that should be addressed right away because it could be causing you to absorb less that u already do.
I also had a similar experience with taking antibiotics. Antibiotics can commonly cause diarrhea or loose stools. Because antibiotics can get rid of bacteria in the gut my assumption is that ppl who have had this surgery actually have more bacteria in there guts then normal which is causing the excess gas and other BM issues. So taking an antibiotic would actually rid that excess bacteria and result in less odor. My GI doc recommends probiotics to help with balancing that bacteria which it did help when I took them.