A few people are saying that if their spines hurt, they would "see a doctor". If you do go to an M.D. make sure it's not just any general practitioner or orthopedist. It's not as if all doctors specialize in or are familiar with cycling-related pain syndromes. See someone who is a cyclist and/or specializes in cycling-related syndromes. Otherwise you'll have just anyone giving you knee jerk advice which may include that you "get a mountain bike".