You say they are "going to fire me" So they haven't fired you yet? When you are fired, you will want immediately to file for unemployment insurance, which will very likely turn out to be your only recourse. The question the will ask you is, 'What happened on the day you were terminated?" and "What did the company tell you was the reason they were terminating you?" and "Had you had any prior warnings that your job was in jeopardy?" You answer these questions, they speak with the company and get their side of the reason for termination, and the unemployment system will determine if you qualify for benefits.
The termination is probably not going to turn out to be in any way illegal. If they have been allowing other workers to do something and then have fired you for doing that same thing, you have a pretty good case for unemployment benefits approval, but not a lawsuit for discrimination unless they had very specific reasons why you were treated differently. And after you've already filed for unemployment, you might want to discuss those issues in your termination with an employment attorney if you think your disability was the obvious reason you were being treated differently, gotten rid of.