After sitting awhile, i cannot put any weight on my leg when i first stand up.

Multiple reasons: You may be compressing a nerve in your leg when you sit down, and when you stand up the limb is numb. The same thing can be the result of compression of a blood vessel. Often happens if you sit on a toilet for a prolonged period of time. Usually positional, and will improve with adjusting how you sit and bear weight. If this does not help, have your doc check your blood flow with ultrasound.