Hello and welcome. This is understandably a frustrating situation. However, HIPAA only protects medical providers from sharing protected health information. It has no applicability to non-medical providers who call medical offices to share their observations about a patient. HIPAA does not come into play at all in that situation.
Likewise, I'm afraid there is nothing illegal about a physician releasing a patient based on a false report that they were overmedicated or a "liability." Physicians, like other professionals, are free to determine who they work with. The only exception for physicians applies in certain emergency circumstances which do not exist based on the facts you have described.
Defamation is a potential cause of action you could allege against the employee who made this false report. However, such a claim would likely fail on the ground that she was sharing her opinion, not an objective "fact" about you. Opinions are not actionable on a defamation theory because, by definition they are subjective and thus not provably "true" or "false." Still, to prevent this person from making similar complaints about you in the future, a cease and desist letter threatening a defamation lawsuit might be effective. The most effective tool moving forward, though, would be to ensure that nobody from your church knows who your doctor is--that way they can't intermeddle in your affairs.
I hope that you find this information helpful. Please do not hesitate to let me know if you have any questions or concerns regarding the above and I will be more than happy to assist you further.
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