What are my options for pursuing legal action against my employer for FMLA violaction?

I am a field researcher for a commercial real estate database company. I live in Tennessee and we work on the road most of the time in new markets out of state. It is a private company with over 100 employees. I have a long term diagnosed mental health disability and had a flare up in October which resulted in a write up (final warning despite no recent prior disciplinary action). My supervisor openly discussed my medical history with non management employees and accused me of lying about my condition both in his documentation and with other non management employees despite knowledge of my diagnosis. Rumors were being circulated of drug abuse also originating with same supervisor. Upon complaint to HR supervisor retaliated by writing me up again this time for a supposed minor infraction. My psychiatrist insisted I take medical leave immediately. My FMLA leave expired at the end of January and my psychiatrist cleared me to return to work Jan. 29 with restriction of no travel for 90 days requiring either (1) local market work or (2) work from home. Employer initially indicated they could not accommodate either. I explained how it would be possible for them to accommodate my needs based on prior work situation and have as yet received no response. It is now approaching a month from my original return to work date. In addition, employer has ignored repeated requests from insurance company to provide information essential to continuance of claim until work situation is sorted. My resources are limited due to being out on FMLA leave and the insurance situation. I am unsure what if anything I may be able to do.