Can a chiropractor collect money from you five years ago?

Five years ago, I've been into an accident. The very next day the lawyer called and wanted me to go see a small private own chiropractor. About a month later, for some reason the lawyer couldn't solve my case so I stopped seeing the chiropractor. The chiropractor said I don't have to pay anything to him but I will be in collection for the x-ray screening that he sent me to the hospital for, so I ended up paying for it as well. Now five years later, he called me last week saying that I owe him $4,000.00. from last 5 years ago. Ok, so can he still bill me? Can he send me to collection?