Was I wrongfully discharged?

I have been working for the same company for little more than a year and was fired today for work performance and was told they are going in a different direction. Last August I was injured and did not report it to my employer. I was a salaried employee and was not concerned about the injury as I thought it was a stiff neck. It was not! I have 3 herniated discs in my neck. I worked for several months with this injury but when it got too bad I went out of work. When I returned to work approximately 7 weeks later I was made an hourly employee and told that I was not dependableand this was temporary and would be reevaluated in 30 days. 30 days past and still an hourly employee. I had a performance review in April that was not great but was given a 2% increase.