1. Your finger popped?.. Anyways swelling, bruise
, unable to bend or extend fingers due to swelling, difficulty in getting a grip indicates soft-tissue injury
+/- bony injury. Chances for fracture
+/- dislocation of small joints of hand cannot be rule out.
3. Xray of hand / wrist will usually guide us
4. Till the time rest to the hand/wrist, ice fomentation, NSAID's, crepe bandage and elevation of limb against gravity will help you to decrease swelling and thereby pain.
5. If xrays show fracture, then treatment is decided accordingly after consulting an orthopaedician.