Are you working now? Have you been fully released by your doctor to return to work with maximum medical improvement? If you are back at work, do you have restrictions? What are the circumstances right now related to your worker's comp case?
If your employer were to fire you for having filed a workman's comp claim, you need to report this at once to OSHA. In fact, if you get fired for any reason very soon, I'd talk to OSHA, because they may be smart enough to pretend there's another reason they're terminating you.
Apart from the OSHA issue of retaliation, if you are terminated from the job, and you have been released by your doctor (even if you're released with restrictions) file at once for your unemployment benefits. DO NOT QUIT YOUR JOB, even if they ask you to do something that will hurt your back again or that you know you cannot do. In this case, respectfully explain to them that you cannot do this, and let them fire you.
When an employer fires you, in order to keep you from receiving unemployment benefits, he must prove he had a valid work related misconduct reason to terminate you.
If you have had more absences or tardinesses than the company policy allows, and you are absent or tardy without a doctor's excuse, this is considered misconduct. If you are caught stealing, attack a co worker, or violate a major company policy, this sort of thing is misconduct. Most of the time, they need to have documented warnings and written disciplinary process leading up to the termination.
So if this "cheap" dummy fires you as retaliation for filing a worker's comp claim, you cannot sue him for firing you, but you can file an OSHA complaint against the company, and you can file for and potentially receive unemployment benefits until you find another job.
In order to get unemployment benefits, you must, of course, be able, available and actively seeking other work. Do not tell the unemployment office that you can't work because of your back injury, or you will not be able to get your benefits, even if approved.
If you are actually terminated by this cheap company, you may want to talk to your state's department of vocational rehabilitation about retraining, finding a job that will not require a strong back.