Is there a law prohibiting the use of a government agency against an individual for vengeful purposes?

There is a dentist who has a vendetta against our office. She is a general dentist and we are a specialist with whom she sent her patients to for many years. She began acting strangely over the past few years and we asked her not to send her patients to us anymore. Ever since, we have been getting letters from the state board from her patients claiming that we should be investigated for violations. She has gotten another patient to try to sue us. Our insurance company deemed it a fraudulent case, and then they took to small claims court. This dentist was their expert witness. We won that case. Not only is she is getting her patients to report us to the State board, she anonymously reported us to OSHA for gross violations. It was the case where the patient took us to small claims court. The dentist, in her brief, admitted to reporting us. OSHA showed up at our office and found no such violations, making only small recommendations and no fines were given. We have been vindicated on all of these attempts. Today, another letter from the state board arrived from another of her patients that we have treated. We are at a loss for what to do.