Ok, you're 21 yrs old and worried about the possibility of a stroke which would be unusual in someone your age. Do you have heart problems? A history of stroke or some other reason to suspect a stroke? Do some research on strokes. The two major types are hemorragic and embolic. Embolic strokes are the most common and occur in older folks, people who have heart disease, diabetes, hypertension, high cholestrol, obesity or certain autoimmune diseases are more at risk for these strokes. Hemorrahgic strokes can occur from brain aneurrysms or blood vessel bursting from hypertension. If you can raise your arm, say a sentence without garbling, able to see straight, walk straight, aren't losing consciousness, you probably did not have a stroke...but if can not do any of these things and have arm/leg numbness or weakness, call or have someone call 911. I would address your concerns with the dizzyness/smell issue with a dr. Good luck.
These sounds more like panic attacks or they could also be migraines. There's a good chance these are not strokes -- you're 21, there are very few reasons why someone like you should be having strokes and if you were truly at risk, you would've already had something more definitive. Try going to your PMD or a psychotherapist and talk about your frequent panic attacks, get some medicine and see if it helps relieve the symptoms.
A stroke happens without warning. But your history states, to me, you have a uncontrolled anxiety disorder. I'd seek therapy to try to find triggers. Of course if you should be sure to be honest.. good luck