Employment Law Questions? Ask an Employment Lawyer.
If you do not have a contract of employment specifically stating that you can only be terminated for cause, you legally can be terminated without cause in your state and almost every other state in the country. This is called "at will" employment.
Now, you allude to discrimination, but you didn't really indicate what you mean by that. You'd have to be able to allege that the only basis for your termination is your race, gender, age, disability or recent FMLA use. You can't just sue for loss of pay without the termination itself being a violation of contract or violation of specific discrimination laws.