I see. I am sorry to hear about your situation. As you're working at a casino, I assume that it's a Native American casino (as I believe all the casinos in Idaho are).
HIPAA does not apply at all because it's the employment context. HIPAA is a health information privacy law, but specifically only applies to providers of health care and associates of those providers (so doctors, doctor's offices, nurses, insurance companies, hospitals, pharmacies and pharmacists, etc...). It does not apply to your employer. So even if there was a disclosure that would clearly and blatantly be a HIPAA violation if it was done by your doctor, if it was done by your employer it would not be. HIPAA is not an employment rights law.
Now while their actions might be actionable by you if it was not a Native American tribe, the fact that it IS a Native American tribe makes any enforcement that much more difficult. That is, your condition could otherwise be covered by the Americans with Disabilities Act (ADA). The ADA requires employers to provide "reasonable accommodation" to otherwise qualified disabled employees, unless doing so would impose an undue hardship (42 U.S.C. § 12181). The problem is that ADA specifically excludes Indian tribes from definitions of "employers" subject to Act. So while "employers", under the law, have to accommodate disabilities, Indian tribes are not "employers" under the law. It's ridiculous, but blame Congress for that fact.
In short, and I'm really sorry to say this, but any limited recourse that you might otherwise have against a general employer would not be there because they're a tribe and largely exempt from most Federal employment laws.
I know this is probably not what you wanted to hear, but it is the law. I hope that clears things up anyway. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (good or better). Thank you, ***** ***** luck to you!