I'm 21; i have been very sick since a flu four months ago. i suffer from postural tachycardia, palpitations, dizziness, chest pain, sweating, terrible heartburn, and vomiting. the cardiologist cleared me but did not get a stress test done. do i have pots

See below: With your GI symptoms, you need to see a gastroenterologist at this point.

POTS possible: Pots is a possibility. You should see a neurologist to have it checked out. Another possible diagnosis is a post-viral syndrome.

Unlikely to be heart: I agree with your cardiologist. Your symptoms are not suggestive of coronary heart disease which is what a stress test is for. Are you staying well hydrated?