Physical stress can cause worse symptoms even if it’s not the cause of your reflux. It’s similar to how training hard while sick will make you feel worse and can prolong the illness.
When I was on FODMAP, I also lost a ton of weight, therefore suffer a lot on the bike because I wasn’t getting the right nutrition. I’ve been dealing with this problem for almost 3 years now and I can say that in my personal experience the worse my problem is ever been, it’s when I was on FODMAP.
I end up going to a Psychology to get CBT so that I can cope better with my symptoms that don’t seem to be going away any time. That helps a bit. But one thing the doctor said that helped me a lot, it is that I needed to find a set of things that would keep my symptoms under control. it took me time a while to find out what that set of things was but I think now I have some type of control to avoid big flare-ups, and continue with my TR training.