Is there any legal action I can take?

Is there any legal action I can take?
In August I was diagnosed with cancer which required surgery in September. My FMLA was approved with planned six week leave. Upon return my former position as Director of Nurses is posted and has not been filled. My Adm. will hardly speak to me. He said they are going to hire someone else. I ask what my position is now. I was told he would have to figure out what he is going to do with me and gave me an assignment below my skill level. I have no reprimands or counseling in my history. My first three days back and I have no job description or job expectation and it is making me crazy and miserable. I am a salaried employee and just beneath the Adm. My surgeon filled the FMLA paperwork out twice before it was approved. I thought it was intended to protect me. I ask if I was a key employee and no one can tell me in HR.
Don't know what to do in Texas.

Can I sue the company for mental anguish and suffering. I have been demoted but have yet been told what my title and job description is. They offered me a night position as charge nurse which is much less than the department head I was. It is embarrassing to tell my patients and families that I am no longer the DON when they come to me. About 3/4 of my staff report to my assistant now. They want me to quit. This is awkward.