My name isXXXXX'm a licensed attorney. I am honestly sorry for your circumstances, very much appreciate your patronage, and am glad to try and help out.
Accordingly, I'm pleased to say that there is an approach you can take to seek redress. First of all, if you haven't already done so and are represented, you should notify your union of what took place. Secondly, they will guide you through the grievance process. Thirdly, you can file a complaint (known as a "charge") seeking relief on the basis of your physical condition alleging a failure of your employer to provide reasonable accommodations therefor. To do so, free of cost, you would follow the steps outlined here:
Federal Sector Complaint Process
This is a process different from the usual civilian approach. There's no way around that, it's mandatory, and complying with deadlines is really important. I'm sure sorry you've been through this, and I hope the future looks brighter for you.
If you have a follow-up question or need clarification, please just say the word by using "reply" to reach me.
I truly hope all works out for you.