have you had an EGD? Was it normal? if so, it sounds like it could be CVS(cyclic vomiting syndrome). It usually starts late night/early morning, but there's no set rules. with CVS you can vomit 10x in an hour. I usually only get a few minutes from when the nausea hits until i'm in a full blown attack. I keep zofran within reach at all times..
To me it sounds like something called cyclic/ cyclical vomiting syndrome. I suggest getting to a gastroenterologist and keeping a log of your vomiting spells, when they happen, and how you feel before and after. Hope this helps!
Sounds like possibly something with your gallbladder. I wou,d get in ASAP to see a Dr. Could be something serious.