Wrongful termination, discrimination

I was recently terminated from my job while I was out on medical leave for a spinal surgery I had in late June of this year. I was over my FMLA 12 week period by 4 days. My employer was given a return to work date of approx. 3 weeks later, and had agreed to it. When I informed them of a few restrictions (no lifting, bending and I need a cane to walk long distances) that my doctor had insisted on, they decided to post my position that had been vacant all sumer, and stated they could not wait the 3 weeks for me to return. They did not make any effort to accomodate my disability or restrictions and further humiliated me by calling me into the HR office (while still out on medical leave) claiming they needed to talk about insurance. When I arrived, they ambushed me (my immediate supervisor was hiding in the corner behind the door) and told me I was terminated. My feeling is that they have discriminated against me because of my disability (ADA guidelines say because I have RA, osteoarthritis and degenerative disc/joint disease that I qualify as disabled) and that they have wrongfully terminated me by incorrectly interpreting the FMLA guidelines. Please advise, since I am anxious to contact an attorney if I do indeed have a basis for a legitimate case. Thank You