I don't know what it is, but I have exactly the same symptoms. Sometimes I can't even manage to produce bile, but still go through the whole-body spasms of vomiting. My consultant says it is probably linked to gastroparesis - a delayed emptying of the stomach, and has put me on continuous omeprazole (related to esomaprazole, both are PPIs).
You really need to go see your GP, tell them that its an on going problem, and get referrals for tests at your local hospital.
In the meantime, think back to what you ate before each episode, see if there's a common factor. I found that large meals, or meals with lots of fibre triggered my vomiting. YMMV