Was this retialiation?

I filed a complaint about unfair practices at my work place. The director is the person who was the focus of my claim. After this claim my division director met with me and did a investigation. My director however started checking everything I did and find fault in everything. My division director claims she was not told who filed the claim. I was out having surgery and she didn't send payment for tuition which is a company policy. I call out sick and was late and was informed to call my director when I was late or absence. This meeting there was no forms or write-ups given so I didn't think it was a serious issue. I was out sick due to a surgery and the director sent my fmla papers late I believe purposely but when I returned from fmla I was terminated two weeks later because I was sick related to my surgery. The director was out of office in washington before I got sick. I was told I was terminated because her cellphone is always on. I believe this is retialiation for my claim and they just need to get me on something. I was employed by this company for 4years and I never recieved a write-up from this director and know I am terminated for a phone call. I did notify the office I was out sick so it is not a no call no show. I just got a mutual seperation agreement paper to sign offering money. I am a supervisor by the way! This agreement states that I can't sue. I am concern that I have a case and this is hush money. Am I correct