I had RNY in 2003....have had very slow weight loss even tho I've followed prescribed diet, routines. I developed postprandial hyper insulinism (low blood sugar after eating a small amount of carbs (5-10 carbs) This has been life threatening. I experienced insulin coma several times before it was diagnosed. Endocrinologists tell me they are seeing more post RNY patients with this very serious problem. If you become sleepy and confused then "fall asleep" 90 minutes to 2 hrs after eating any carbs I urge you to get a glucose monitor and check your blood sugar when you start to feel tired or confused. My blood sugar has been as low as 28 after a doctor had me eat a bagel so that he could " see it happen." He had not believed me but after that he understood what I was talking about. I take acarbose if I know I will eat 10 or more carbs ( 1/2 a slice of bread!) and it does help. Doctors who have not seen this may be skeptical so get a glucometer at the drug store and check your own blood sugar. I can fast for 24 hrs and have normal blood sugar...But eating carbs will put me in a crisis state immediately.

The condition you are experiencing is called reactive hypoglycemia. A few patients after gastric bypass surgery experience this condition. Reactive hypoglycemia (postprandial hypoglycemia) refers to low blood sugar that occurs after a meal — usually within four hours after eating. Signs and symptoms of reactive hypoglycemia may include hunger, weakness, shakiness, sleepiness, sweating, lightheadedness and anxiety.

These links discuss the condition:

https://www.ridgeviewmedical.org/services/bariatric-weight-loss/enewsletter-articles/reactive-hypoglycemia-postgastric-bypass

http://spectrum.diabetesjournals.org/content/25/4/217 [Most patients with dumping respond to nutrition modification, comprising frequent, small, low-carbohydrate meals. In this article reactive hypoglycemia is referred to late dumping syndrome.]

http://www.weightlosssurgery.ca/before-after-surgery/reactive-hypoglycaemia-post-gastric-bypass/

https://www.stjoes.ca/patients-visitors/patient-education/f-j/PD 7972 Reactive Hypoglycemia after Bariatric Surgery.pdf

I've had this happen to me a few times. Once, I literally passed out and woke up about 2 hrs later. Shoved in some sugar and was fine in a bit. NOTHING to the extent you have. I do see some sequela with long term RNY (2003 also), but I'd change nothing. Still glad I did it. Just adapting as need be. Hope you're better.