Unlawful termination after being on FMLA

I worked at a retirement home for almost 2 years. A new person was hired and I trained her to cover my maternity leave. I left on FMLA 6/1/06 and was released 7/1/06. They did not have a job slot for the person they hired to cover my maternity leave, so they made a position for her...overall chargeperson on the weekends. I worked 8am - 12am back to back Sat and Sun. That was my schedule that I was hired for. They had her work 6am - 10pm Sat and Sun. They fired me and replaced me with her 28 days after I came back from FMLA. They no longer have two medication aides working on the weekends. Basicaly it seems as if they made up a position for her until they could terminate me. I was handed 3 write ups in one day (I had not recieved a write up in the two years that I worked for the company). I was called while on maternity leave by a co worker and told that the person covering my maternity leave was to be replacing me. I told her that that was illegal. I was gathering evidence to report them to state prior to FMLA,because of major medication errors. I was told on more than one occasion not to tell the family members of these occurances. I believe that they knew I was to report them to state, they waited until they could find a reason to terminate me. Do I have a case for unlawful termination?