The federal agency in charge of the Health Insurance Portability and Accountability Act (HIPAA) of 1996 (HIPPA) is the Health and Human Services Department. The complaint mechanism for a person to follow is to go about filing a complaint with the federal Health and Human Services department if you have experienced a HIPPA violation. The federal HIPAA statute does not provide anyone, including any person, with a private cause of action in the courts. This means that even for a violation by your doctor or other medical personnel, a person cannot bring a lawsuit. A person may, however, use the complaint mechanism by filing a complaint with the federal Health and Human Services department. That HHS Department can and may follow up on a reported HIPAA violation. Complaint forms are available on the Internet.
It seems to me (perhaps wrongly -- not sure) that part of your quesiton is really venting about your ex and a potential conspiracy among the doctor's office (your target here in the question) and the ex as againt your rights as the custodial parent. If that is the underlying issue then perhaps seeking a modification of your divorce decree concerning parental rights and child custody, etc. may be the way to get things improved from where you stand now.
My answer is not intended to be giving legal advice and this topic can be a complex area where the advice of a licensed attorney in your State should be obtained.