My finger sometimes makes a cracking noise and hurts when i bend it. if i pull hard on my finger before bending it then it doesn't hurt or crack.

Should see MD: You may have injured tendons around a joint. Suggest you visit your doctor. You could try soaking in warm water and then gently squeezing a rubber ball. Best to see physician first. Stop pulling on your finger. You may injure yourself further.

See a hand surgeon: you might be having some kind of tendinitis that is locking your finger a hand surgeon will examined you and give you a proper advice

Trigger finger: It sounds like it may be an overuse syndrome like a trigger finger. Try limiting use of that finger for the next 2-6 weeks, if possible. If it persists, please seek help from your physician. Sometimes a finger splint with immobilization can help.