Help! I keep having dizzy episodes and I don't know why

When I was like 16, I had my first dizzy episode. I woke up incredibly dizzy and vomited because of the spinning. I couldn’t walk, move my head too fast, or lay on my back. It was debilitating. I’ve had about 5 dizzy episodes since then. My last one was in November I think. I woke up in the middle of the night, felt dizzy, couldn’t fall back asleep, turned on my side too fast and instantly became nauseous; I had to run to the bathroom and puke. But then it was over. I’m SO scared of having another episode, but I don’t even know what this is, so I don’t know how to prevent/fix them. Please someone help, what is happening? Only three of them I can think of a cause: first one I rode a jet ski for like 3 hours, second one I played an old wii game with bad graphics, third one I played a side scrolling video game for way too long. I don’t know if info that helps.