Demoted after FMLA Leave

After 6 weeks of unpaid maternity leave, I returned to work and found out that I was demoted because my military husband will be transferring in a year. (IN ONE YEAR) My pay stayed the same, but work conditions worsened by the day. I was in a managerial position for over 2 years and moved to a file clerk status. I was yelled and screamed at every day after returning from leave because I did not ask permission to go to the bathroom, I did not handle my new job properly, I did not say "good morning" to the office manager. Everyday it was something new they were complaining about. I never once received a complaint in my previous position, but since I returned from leave, they were trying their best to get me to quit. Stress and anxiety finally got the best of me. I resigned and left the business. Another employee took materntiy leave a few weeks before me and had no problems being reinstated in her job. Do I have a case here?