Doctors can you tell me why can't i stop cracking my neck and fingers!?

Habit and/or feels : Good! this is ok and you are doing your own spinal manipulation like cracking your knuckles. You are most likely "cracking" your facet joints (the small joints of the spine-2 at each level) which stretches their joint coverings or capsules which causes a reflex relaxation of the surrounding muscles. There is no harm in you doing this. The same goes for your fingers.