National origion discrimination

Hello, I Have been employed for state for past 6 years. on march 2009 I was fired and my wife asked to resign for a reason stating " Unacceptable personal conduct" the conduct was I was making a personal phone call during a company time and company resources, but this is a common practice in all areas of I work in this company. this company has 6500 employees and I seen it all the time that employees making a phone call, this been said, I have never given any warning or said any thing written about my calls for the last five years and the phone record have been given has a lots of other personal phone calls from different area of the company. but I feel I was fired for national origin discrimination based which started about 3 years ago my second manager conversation with me. the conversation was that I ask to leave 1 hour earlier to go for Immigration appointment in next day, my manager stated " He doesn't care about my immigration process and he will not let me leave. since that conversation my manager is treating me different that any other employees and 3 other managers have told me that I need to work on the days and the time that my manager is not working they stated that he doesn't like me. and I believe that is where the problem is started. Even he was not my immediate manager, since then he always talk about bad and look for any kind of mistakes I am going to make and report it to my director. now I am fired for a reason that the all company employees are practicing and me and my wife are the only one who is fired for this reason. do you think I have any discrimination case specially " National origin " ?
Thank you!