Can bullying an employee be considered as discrimination?

I feel like my previous manager bullied me out of my job because I stood up for myself and didnt allow him to disrepect me. The manager had displayed disrespect and sarcaism in a meeting in front of other employees. I felt the managers actions were wrong and rude and after the meeting I pulled the manager aside and explain to him that it wasnt appreciated. From that point on, I feel like I was targeted to be terminated. I was miss treated while recovering from a work related injury which happened after our confrontation. Once I returned to work only 3 days later was terminated for insubordination that did not take place. The HR department r suppose to be investigating the manager but nothing has been determined yet.