Yesterday i got very dizzy where the room was spinning for over an hour. I thought its either vertigo, or a reaction to a claritin pill i took that was oldish and I've never had before. Could this be claritin or probably vertigo?

I was explaining to my doctor about a bout of disabling giddiness.

"I was walking home along the top of a cliff when suddenly the entire world started spinning."

"Had you vertigo?" he asked.

"No, only a couple of miles."

also, i still feel nauseous, not as much as i did yesterday but I'm afraid to go to school. And my stomach and head hurt. The medicine should have worn off tho.

I highly doubt it was the Claritin that caused your vertigo. If your sinuses are acting up due to allergies, it could be affecting your inner ears. I've dealt with vertigo for many years and the best advice I can give you is to make a Doctor's appt. And get your ears checked out. He/she should be able to help you a lot more than any of us can. Please see your Doctor.