I had asked for some further information and have not heard back, however, I can relay some information about HIPAA.
First of all, if there is a violation of HIPAA, it would be by your doctor. The requirements for HIPAA are placed on the healthcare practitioner that maintains the medical records. Anybody can call the doctor or run into the doctor at a store and ask about confidential information, but it is the responsibility of the doctor to not divulge the information if it is not allowed under HIPAA.
If the Social Service worker was providing treatment, then sharing the confidential information is allowed under HIPAA. HIPAA states that the information in the medical record can be shared with any healthcare practitioners that are providing treatment to the patient. This use of confidential information does not require authorization for each use of information, although the fact that the information may be shared should have been told to the patient in a Notice of Privacy Practices. On the other hand, if the Social Service worker was not providing treatment, then the doctor should not have shared information in the medical record without authorization from the patient.
If the doctor shared information inappropriately, then you may have a claim against the doctor. about a HIPAA violation. The only way that you would have a claim against the Social Services worker would be if they were dishonest in the process of getting access to the medical record, but that would usually be brought under state law, rather than under HIPAA. In addition, if the doctor relayed false information to the Social Services worker, then there may be a claim against your doctor about a deviation from standard of care.
If I can provide any clarification, please let me know.