I was diagnosed with endo 17 years ago. I've had lots of issues with it, including bowel adhesions, but over the last few years I've suffered with chronic indigestion. I ended up with gastritis and now take meds every day to prevent this. But, my stomach pain and acid reflux still gets worse the week before a period.
During tests for my stomach, an ultrasound picked up a polyp on my gall bladder. When I had my last lap I asked if the gynea could take a look and see if that, too, was endo. She couldn't get that far, but she managed to take a look at my liver which was of 'fibrotic' appearance in the crease of the liver.
I have a healthy diet and exercise regularly. I've since had my liver checked and it's functioning normally. I saw the photos and, to my non-medical eye, the stuff on my liver looked like the same stuff created by the endo that leads to adhesions.
Anyway, it would be interesting to know if anyone else with endo gets stomach pain and acid reflux before a period.