When i get up from a sitting position, i feel shaky and get a "passing out type of sensation". lasts 5-10 secs then goes away. even when laying down.

Orthostasis: You more than likely have ortho static hypotension. There are multiple reasons including medications, dehydration and autonomic dysfunction.

Near-syncope: Your symptoms merit a careful history and physical exam, including a check of your blood pressure, sitting and standing. That would likely provide an answer. If not, then further testing might be warranted.