Constant nausea but no vomiting?

[CamDiMaria]

Okay, so for like 10 days, my mouth has been extremely dry, and I have felt nauseous, but have not vomited yet. It's all in my throat, my stomach is fine. It almost feels like there is something in it, and the feeling is worse when I am laying down. I was tested for mono, diabetes, hyperthyroidism, and a couple other things that I don't remember, but they all came back negative. Other than this, I am in pretty good health, but it's starting to have a negative impact on my life. I've missed a few days of school and I just don't even like leaving the house because I'm afraid I'm going to vomit. Any help is appreciated, thanks.