Most of the comments in this thread are, to put it delicately, obviously not written by a lawyer.
The posts that claim you're just out of luck because you can be fired for having a disability if you're an at-will employee are particularly off base. That's just completely and utterly wrong in the United States. Furthermore, your post doesn't say where you live and Canada doesn't even have at-will employment in the private sector (and they do have 7-11s).
It's not a coincidence that the only posts in this thread that make any sense are the ones written by a lawyer. Listen to him when he tells you to find your way to an employment lawyer (not just any lawyer), talk to that lawyer about what happened and get a real legal opinion about your case. No one on this thread (including me) can tell you how strong your case is, but it's certainly strong enough to warrant getting a real legal opinion.