Do I have Hypoglycemia?

I have been dealing with this for almost 20 years. It started out just a few times a year, then once a month, then once a week, then every day, & now sometimes, more than once a day. I have been to all sorts of doctors, & nothing has for sure been figured out yet. I have had all kinds of tests. (gall bladder, pancreas, liver, blood sugar, ulcer, etc.) I will feel  fine one minute, then feel like I have the flu the next minute. I get hot/cold, shaky, sometimes light-headed, weak, tired, then nausea, then vomiting & sometimes diarrhea. I eat a snack to try to prevent it, but sometimes it still happens. I go through all this until I vomit. Then, I force a meal down, & after I eat a "meal", it goes away within about 20 to 30 minutes. I have almost passed out. It gets worse the older I get. I have been checked for low blood sugar, but it is never below, except one time it was borderline. It normally is worse between breakfast & lunch. The Dr. put me on prevacid, & this helps me not vomit as much. Does anyone have any other suggestions or think this is hypoglycemia?
The Dr. found polyps on my gall bladder now, & may remove it, but he doesn't know if this will take care of me getting sick, because I normally don't get sick after eating like most people. I feel better. Could it still be hypoglycemia too? I don't get much pain either with the gall bladder polyps. It is just weird. & remember, this has been going on almost 20 years, & now the polyps just showed up. Please help me. I can't take this anymore.