What to do if i cannot stand up for more than 10 minutes. i feel terribly sick and feel like fainting?

Low blood pressure: Feeling sick and as if you were about to faint are symptoms associated with low blood pressure upon standing up, also called "orthostatic hypotension." This should be evaluated in a doctor's office where heart rate and blood pressure can be evaluated while sitting and then while standing. Possible causes include medications, carotid narrowing, and adrenal dysfunction.