How to Fix My Ps3 Controller?

Everytime I play Call of Duty, I try to spring with the left analog stick, but then it does a half sprint then crouches. Then I try to sprint again (left analog) and it takes out a new weapon (Triangle button). Is there something wrong with my controller or the analog sticks? Is there a way I can fix it?

Suggestion:

Take it to Gamestop and have them fix it