You may have some options, but more information is needed to answer your question. If your employer is covered by the FMLA (it applies to most employers with more than 50 employees), you have the right to 12 weeks of unpaid leave for a serious health condition. After 12 weeks, your job is not protected. Under the Americans with Disabilities Act, if you have a disability, the employer has to make a reasonable accommodation for your condition. However, even if you have a disability, if you can't perform an essential function of your job, you may not be protected. You should speak to an experienced employment attorneys as soon as possible to see what options you have. Many of us will provide a free initial consultation.
This answer is provided for informational purposes only and should not be relied on as legal advice. You should be aware that no attorney-client relationship is established through this answer and none will be established without a personal consultation and the signing of an engagement agreement.