If she was able to perform all of the essential functions of her job with or without an accommodation such as additional time seated, then she might have been a qualified individual with a disability. Had she been the victim of disability discrimination, that would have violated both the Pennsylvania Human Relations Act (if she was one of at least 4 employees) or the Americans with Disabilities Act (if she were one of at least 15 employees).
However, both statutes require that a claimant first exhaust their administrative remedies before filing a lawsuit by filing a formal charge of discrimination with the Equal Employment Opportunity Commission or the Pennsylvania Human Relations Commission. Those charges must be filed within 300 days of termination, which is close to 10 months.
So you are at least two years late in even contemplating any cause of action.
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