Ok so l was taking my back swing at the driving range to day and when l was coming down to impact, My back had this stabbing, peircing pain going through it. What did l do to it? My coach said l tried coming through way too quickly.

Sounds a whole lot like:
A: you bulged a disc
B: you slipped a disc
C: you pinched a nerve
Any one of which makes you use words you did not even know you knew! :-)

Honestly it is probably a simple strain rather than anything to do with the spine itself... l would however advise getting it checked out...could have bee caused by an over rotation or any of several movements that may have been out of sync.