I have a theory........the doctors don't have any idea what they are doing, or they do know exactly what they are doing and make money by putting you through diagnostic tests to make their house payment. I went through about 15 years seeking an answer to the question you have. I was put through years of testing and prescriptions.........nothing helped. My teeth went bad from the acid reflux. My gastroenterologist told me that I had the stomach lining of a 90 year old woman (I was 40 at the time) and he said I would likely die of stomach cancer. The food would sit in my stomach and rot, deteriorating the lining of my stomach. The reason your stomach and digestion is slow is due to the largest nerve in your body not functioning properly. It is the Vagus Nerve. It moves the food through your digestive tract. The reason the nerve doesn't work is that you likely are diabetic. High sugar will cause the nerve to stop working. None of the doctors I went to suspected I was diabetic because I was not obese, in fact I was very thin. I had type 1 diabetes for years. It caused horrible digestive problems, expensive dental issues, I was exhausted......wanted to sleep all the time. I had a white coating on my tongue. My dentist sold me a very expensive mouth wash......when he should have recognized it as Thrush which is YEAST.....it grows rampant in diabetics when their sugar is not controlled. I had multiple vaginal yeast infections and the doctor who finally diagnosed it was my OBGYN. A simple blood test- called an A1C can show if you are diabetic. Once you get your blood sugar levels under control, then you will not have digestive issues. The nerve will begin working and you will find that you are quite angry at the medical community for either ignorance or greed- not sure which it was in the case of my many doctors. Many of the doctors would hand me prescriptions for anti-depressants.........making me more frustrated, but I would tell them I was exhausted and that was their answer. Good luck. I hope this helps.