I'm a 20 year old male. 6'2", 185 lb. I've been donating blood for about two years, and every time I donate my blood pressure is usually around 145/75, which is high, but not horribly high. I've always had orthostatic hypotension, but recently i've also been getting lightheaded sometimes when i'm just sitting. After last time I donated blood, I felt a little lightheaded (not to the point of passing out though) for about two days. I also having been feeling for the last several months that I can't get a full breath. I try to take a deep breath, but my chest feels tight and I can't breathe in anymore before I actually feel like i've taken a full breath. I though it could be asthma (my father has it), but i've had two spirometry tests. The first one placed me about 10% under expected, but the second had me right on for my age. So this causes me to think that it may not be lung related. I know chest tightness can be a symptom of heart problems sometimes. Any thoughts on what might be wrong with me?

Thanks-
-mike