Should I sue for what I feel is retaliation?

I am a nurse that works a skilled floor. Two weeks ago my ADON asked me to change a skin assessment I did more than a month ago. This would be considered Medicare fraud and is illegal, besides the fact that I would be lying so that the company can benefit. I told her no and then reported this to the DON, which is the main nurse boss. Little did I know she put the ADON up to it. So I reported this whole incidence to the administrator. Two days later I was put on leave with pay until they investigated this. The people I accused did the investigation, real fair huh. So today I get a call saying I am terminated for insubordination and creating a hostile work environment. I been there 4 years and have never even been written up. Does this seem like its a form of retaliation?