Unfortunately, the Chiropractic seems to be riddled with pseudoscience...I don't see any major warning signs with what you describe, and maybe this guy can help you...as I understand it, you should never, ever let a chiropractor do neck manipulations, and if they start talking about 'sublaxations' or claiming crazy stuff, run away fast. References:
Don't Let Chiropractors Fool You
and:
Tips on Choosing a Chiropractor