Employers cannot retaliate against you for taking FMLA leave to care for a relative. There may also be an associational discrimination claim. I suggest speaking with an employment lawyer immediately.
Whether or not you are eligible for FMLA leave depends on factors such as how many employees the employer employs at a location, how many hours you worked for that employer, the nature of your relative's condition, the nature of the documents submitted regarding your relative's condition, and your communications with the employer regarding the requested leave. I recommend consulting with an employment lawyer such as myself.