There are many different issues which arise from your question. Certainly, you have 1st amendment freedom of speach rights which allow you to talk about your experience with this doctor.
However, if your speach is defamatory to the doctor, he can sue for libel. Please understand that truth is an affirmative and winning defense whenever you are accused of libel.
You may want to discuss your problem with a lawyer in more detail. Most lawyers on Avvo, including myself, offer a free phone consult.
Andrew M. Jaffe
Attorney at Law
Practice Limited to E-Commerce and Internet Law
This post is provided for general informational purposes only and is not intended to be legal advice specific to you. This general information is not a substitute for the advice of an attorney in your jurisdiction. The attorney client relationship is not established by this post.
Your statements are likely protected so long as they are truthful. The doctor could sue for defamation or libel, but truth is a defense. You likely will want to consult a lawyer in your state as the laws regarding defamation are different from state to state.
For more information on the topic of online defamation, I've included a link to my firm's free 30-minute webinar recording on this topic.
This answer does not constitute legal advice, and by answering this question we have not entered into an attorney-client relationship.
If all you said was..."shared my experience, telling what happened and that I would never visit a chiro again..." and your statement contained no misrepresentations, he would have no actionable right to sue you. If he could prove that part of your statement was false, he might have a successful claim against you.