In terms of chiropractors, I found that going to one helped my back problems (sacroiliac issues), but a few years later when I started having neck pain, the chiropractor made things worse. (Eventually I figured out that my posture while sitting at work caused most of the neck problems.) My trainer's brother is a chiropractor, and his advice was that they can be helpful, but they can't cure everything, though some of them think they can.

In terms of places to ride off-road, there is a mountain biking club in this area that is a great resource for finding places to ride. They are affiliated with IMBA. Maybe there is a local club in your area. Also look into regular cycling clubs -- one of the clubs I belong to primarily do road rides but they do have a few people who lead mountain bike rides and know all the trails around here.