Does the non-compete clause differentiate between you leaving on your own, ,being fired, or leaving due to an injury? And, if you could not perform your duties for them, ,how are you going to compete with them?
I may be guessing or not licensed in your state. No atty/client relationship exists.
From the supplementary information you added to another attorney's answer, it appears that your company is trying to hold up your last paycheck until you sign another non-compete. Your right to your paycheck is absolute and your company can't make it conditional on anything.
As for the noncompetes, they're only valid if your employer offers you something in exchange for them, whether it's being hired in the first place or given additional money or perks, etc. If the employer is saying that you can return to work when your back's better, it doesn't sound exactly like a termination. Maybe it is, maybe it is something else. You should not rely on general advice on this website. Instead I recommend that you speak with an employment attorney. Have him or her take a look at the two noncompetes and give you some personal advice and a strategy.
If my answer was helpful to you, I would appreciate if you would mark it either "helpful" or "best answer" if you feel that applies, as AVVO gives us rating points based on feedback. Thank you! Please note that the above answer is not to be construed as legal advice. It is my personal opinion based on your question, and it was given without obtaining the detailed information that I would normally request in order to render comprehensive legal advice. I advise you to consult with a local attorney of your choosing to obtain specific legal advice. The fact that I answered your question does not create an attorney-client relationship between you and me.
The answer to this question depends on the specific circumstances. While a non-compete may be valid in Pennsylvania if reasonable, there is case law to support that it should not be enforced in equity where an employee is terminated for performance reasons. In brief, appellate courts have reasoned that if an employee is deemed to be "worthless" to the employer, in fairness, it should not keep the employee from obtaining employment elsewhere. As mentioned, however, the outcome is fact specific and you should consult with an employment lawyer on how to proceed, especially given that you state you were terminated due to a back injury and there may be other potential issues for an attorney to explore.
Any answers provided are informational only and without an in depth review of the particular facts and circumstances. I only offer legal advice after I enter into a written agreement with clients and after a review of the specific facts in a case.