I've had black bag eyes since I was a kid.
I also have acid reflux and IBS kind of issues. Sometimes I've had extremely painful episodes of it. Unsure of the cause, but I know at least some of the time it's anxiety/stress. And I could probably improve my diet, which is tough when fruits and vegetables have revolting textures, but I really have tried to find ones I can tolerate.
Avoid acidic food and drink, alcohol, coffee and high fat foods. Drink lots of water (2L a day) and eat more high fibre foods. If it's really bad, go to your doctor and maybe he/she can prescribe you some medication to take to decrease your stomach acid levels. 