Chiropractors are not quacks. They are not always the right choice - that depends on what's wrong - but what they do works. I say this as the daughter of a chiropractor.
Their approach differs from that of traditional medicine, which focuses more on pills and surgery. Physical therapy is also not the same as chiropractic manipulation, though chiropractors may sometimes prescribe certain PT-style exercises.
There are good and bad chiropractors. There are also good and bad neurologists, and I've experienced a number of those.
I've also had PT worsen my condition to where I couldn't walk. That wasn't the fault of the physical therapist, who was only going on doctor's orders and diagnosis. That was because there was/is more going on with my knee than that one problem. It didn't get better until I gave up on the PT and just stayed off it as much as I could. Basically, it needed to rest and heal for several months.