Why can't I go more than two hours between meals without getting sick?

[Xandra555]

For about two years I have had an almost constant gnawing feeling in my stomach. My throat gets extremely tight and I feel as if I haven't eaten for days when this occurs. Even if I eat a large meal I am hungry again within an hour and if I only eat small meals throughout the day I am constantly famished. It starts as soon as I wake up, gets progressively worse throughout the day, and ends only when I go to sleep. I'm also not able to go more than two hours without eating or I experience extreme weakness, nausea and an "out of it feeling". I cannot think when this happens and I feel as though I am dying. Eating provides relief but it can take up to a few hours to a few days before I finally feel better after these incidents. I should also mention that I am exhausted all the time even though I sleep an average of ten hours every night.

I've had an endoscopy that showed no erosions or ulcers but did show that I have mild chronic gastritis. I do know that gastritis can cause a gnawing sensation in the stomach but what I don't understand is why I experience the episodes I do when I don't eat. I have checked my blood sugar during several of these episodes and it is always within normal range (4-6). I have also had ultrasounds done of my liver, kidneys, gallbladder  and pancreas, all of which were all normal.

As for diet, I only eat lean meat, vegetables, rice, gluten free bread and low fat dairy. I do not drink alcohol, coffee or pop, only water and decaf tea. I was of average weight (5'6 125 pounds) two years ago but keep gaining weight because I am not able to stop eating. I also had to discontinue exercising in December of 2014 due to fatigue.

If anyone has any suggestions as to what this could be it would be greatly appreciated.
Thanks.