Well i have stiff fingers either when i'm holding a plastic bag to holding a tennis racket. i also have double joint fingers. is that the case?

Joint stiffness : Stiffness is different than hyper laxity . The hand stiffness may be do to joint or tendon problems- this should be evaluated. The hyper laxity or double jointed should also be evaluated - there are medical conditions that could cause this.

Not Sure: I am not sure what you are having trouble with. Stiff fingers usually mean that they don't move easily, or feel tight or swollen when trying to move them. Double jointed individuals do not have "extra" joints, they tend to be very flexible which allows their joints to move in ways most people can't. Over use of flexible joints can cause some inflammation and stiffness. I hope this helps.