At night, around the same time each night I feel really nauseous and sick. And I feel like I'm going to throw up. It's been like this for a really long time now, and I don't know what's causing it or what's wrong with me, but I'm beginning to get worried & I just want answers!

Have you considered going to a doctor to get checked out? There's not much that any of us can tell you other than the obvious.