Do I have legal recourse if my employer is changing my shifts because she is mad that I had surgery?

I have worked as a Sonographer for my hospital for 5 years. I was hired as a Sonographer and to help in X-ray as needed. Last year, one of the Radiologists remarked in a joint board/management meeting, " that I was the best Sonographer in any of the 60+ hospitals they read for in Oklahoma and other states. " Since that time, my supervisor has been literally going through trash, watching security cameras, following me, interrupting exams to tell me I have a patient waiting, writing me up on very thin to nonexistent information, and verbally attacking me and accusing me of "not working" "not being a team player" "not helping X-ray ". I have scanned 12-16 patients a day. I am scheduled every 30 minutes and accept add on patients with out complaint. I became very ill and was for 2 weeks, I had an appointment with a surgeon to discuss planning a future gallbladder removal. My supervisor told me that I had better be sure to get that done after the first of the year, as I was scheduled very heavily until then. I discussed this with the doctor, and we made a plan to hopefully keep me going another month. The plan didn't work, I became very ill, vomiting until I was severely dehydrated . At this time I was admitted to the hospital as an emergent surgical patient. My gallbladder was removed, with some difficulty, as it was infected and starting to rot inside my body. I was not cleared for work for 3 weeks, and my surgeon really wanted me off 2 more, but because of the nature of my work, he let me go back to work. Upon my return, my supervisor called me into her office and told me that I was being transferred to X-ray working Saturday, Sunday and Wednesday nights. I was to spend a week in CT scan to refresh me then start the new shift. I asked what brought this on, and she said to me ,"you are going to learn to be a team player". I am a 47 year old professional woman, with 18 years experience in my field. This is crazy to me. Do I have any legal recourse?