My question involves labor and employment law for the state of: MO
(small company)

After having a bypass surgery and given a medical leave, I was instructed by the doctor to return to work but working under partial days only for a two weeks and then full time.
My boss while always sympathetic with my condition, completely ignored my condition and with psychological threats (you okay to travel? because you know how our boss is ...., etc.) So I had to travel with him for the whole week and work 60 hours.
While I find their behavior unacceptable and unethical, is there something I can do legally?