When i bend my left wrist back, there is sharp pain that shoots to the tip of my pinky?

Compressed nerve: Sounds like similar symptoms as in ulnar tunnel syndrome ( similar to carpal tunnel). More info http://bit.ly/2fhcU8G. You should get it evaluated to confirm a diagnosis and see what the cause is, especially if there's some numbness involved or you can't grasp objects properly as a result.

Ulnar neuropathy: A pain that shoots to the tip of the 5th finger on extending the wrist backwards can indicate an Ulnar Neuropathy. Most often this is due to compression of the ulnar nerve at the level of the elbow and often occurs in weight lifters from bench pressing. Occasionally it can occur at the level of the wrist or rarely the axilla. For additional information > http://bit.ly/1p3Cqvh