I'm 17 years of age, and I crack my knuckles a lot. I crack the very tip of my fingers and I've noticed that my fingers look kind of slanted to the right at the tip. Besides that, I bend my fingers back to crack them. So randomly, like once every 2 weeks or every month I get this sharp pain. It lasts for about 40 seconds and stop.

What could this be? Is it serious?