Being on Social Security disability will not affect your right to bring a lawsuit against your employer for unlawful employment termination but very well may affect the damages you may recover. One of the elements of your potential damages in that lawsuit, meaning how much a court or jury could award you, involves your loss of earnings by being unlawfully terminated. On the other hand, qualifying for Social Security disability benefits proves that because of your disabilities, you cannot do any jobs that exist in significant numbers and the national economy. It very well may be that a jury would not award you as much money even if they found you are unlawfully terminated since as a result of your SSD award you would not be working in the future anyway. When you consult with lawyers about your employment discrimination claim, that is one of the first things you need to discuss with that lawyer.
Disclaimer: the above does not constitute legal advice and is only an opinion of the author as to current law. You should consult an attorney with questions about your particular situation.
If you haven't already, you need to speak to attorney on this one. By being placed on SSD, you are basically saying you can no longer work, but in a case for wrongful termination part of your damages will be claiming future wage loss, which you are essentially incapable of. I think a good workers' compensation attorney would be a good start for you. If you can't find one locally, feel free to contact me.