The past week ive felt dizzy at times like when im changing positions in bed, changing my head angle, and looking down. one time i was sweating soon after i feeling like my head is spinning. what could be causing this and when should i see a doctor?

The type of dizziness you describe is consistent with vertigo, which is related to the inner ear & has several causes: infection (often viral), inflammation/neuritis, trauma, or rarely, a tumor (not likely @ your age). Viral infections usually last just a few days so if symptoms have been present longer than that you should see Dr for thorough history & exam (esp Neuro exam) to evaluate