At 20, hw do II get a dr to run test on my fingers? Sometimes they lock up a&now pain on my index finger. Wat can this be?

Trigger finger. Most likely this is trigger finger- the flexor tendon mechanism in the palm at the base of the finger is not gliding properly through the first pulley in the finger which holds the tendon in place. The test is an examiner familiar with this condition such as a hand surgeon.
Fingers stuck. I think there are 2 problems here. 1) your fingers getting "stuck" usually indicates a tendonitis of the tendons that move your finger. With inflammation they get stuck at times. A cortisone shot will relieve this. 2) the cause of the pain in your index finger is not clear but could be arthritis (a cortisone injection may help, or otc ibuprofen) or it could be severe inflammation related to tendon.