Dealing with a deteriorated bulging disk myself. You didn’t mention the type of bike that you’re riding, but going from a hardtail to a full suspension made a big difference for me. Had to bite the bullet for the extra money for a full suspension but it was defintiely worth it. As far as exercising and stretching goes, you have got to do it everyday. Spend extra time on the hamstrings, that’s probably where your weakness is. Good luck and keep moving.