My daughter was out of work and in the hospital. Her manager told an emloyee in another business what was wrong with my daughter without her permission.
Isn't this a violation of her privacy?

Privacy, possibly, HIPPA, no.

HIPAA protects patients from having their medical diagnosis and treatment revealed by a medical practitioner to a third party without their permission.

Your daughter's manager was not providing her with medical care was he? I assume he found out from your daughter.

Which this may have been a breach of privacy and ethics, it has nothing to do with HIPAA and is probably not actionable.