You should NOT be negotiating with USAA (or any other insurer) on your own. Insurance companies LOVE it when accident victims deal directly with them—the cards are stacked against you. That said, as a general rule, where you are claiming an damages from an injury, your medical record and information is fodder for the dialog. See an attorney ASAP and have a consult--many offer free consults.
What harm did you suffer? You were not turned away, you checked yourself out. You didn't get a private room and they were unpleasant to you? Is that your claim? Where were you for the four hours before they sent you to the
crowded triage room?
See a NV Medical malpractice attorney who may be able to tease out additional facts, but I don't think you have any case.
I am not a FL attorney, but based on experience suspect the detainer acronym stands for: ‘ORL MDTN likely means 'Orlando Midtown'; NTFY P&P likely means 'Notify Parole and Probation'.
See attached link scroll to bottom of the page: http://www.dc.state.fl.us/facilities/comcor/09.html
FWIW, nothing in your post would entice an attorny to donate tens of thousands of dollars to your cause. Most attorney's who do pro bono work do that work through legal aid organizations unless the matter is one of sweeping injustice or wide ranging public policy. No elements in your narrative suggest anyting other than you want something substantial, free of charge.