You need to engage an experienced employment law attorney, in your area, who can contact your employer and set them straight about making false assumptions without any direct knowledge of whether you have any physical limitations. The attorney can help you try to get your hours back and caution the employer about potential retaliation.
To find an attorney, you can either use the "Find a Lawyer" function at the top of the Avvo page or go to the website for the California Employment Lawyers Association at www.cela.org and search for a CELA member whose office is in your area.
They say you get what you pay for, and this response is free, so take it for what it is worth. This is my opinion based on very limited information. My opinion should not be taken as legal advice. For true advice, we would require a confidential consultation where I would ask you questions and get your complete story. This is a public forum, so remember, nothing here is confidential. Nor am I your attorney. I do not know who you are and you have not hired me to provide any legal service. To do so would require us to meet and sign written retainer agreement. My responses are intended for general information only.
Your employer, perhaps unintentionally, is engaging in perceived physical disability discrimination. From your description of the factual background, you do not appear to have a disability that significantly limits your ability to perform the physical requirements of your job. The employer cannot simply assume that you have such limitations from the fact that you had back surgery last year. Even if the employer reasonably believes that you have such physical limitations, it cannot drastically cut your hours without first exploring with you what reasonable accommodations it could make that would permit you to work a full schedule. You should consult an experienced employment law attorney to contact your employer on your behalf. Your attorney should be able to negotiate an appropriate resolution of the problem with your employer's counsel or human resources manager.
I agree with my colleagues on this one. My one concern is that you might have failed to disclose any physical restrictions your doctor might have given you after your surgery. If you have been released with no restrictions, or with restrictions that do not affect what you do on your job, you are fine. If, however, your doctor placed you on some restrictions that you have been violating so that you could get the job and keep it, you might have an issue.
If you are unsure about whether the doctor gave you restrictions, you should make contact with him or her, and then consult with an attorney who is knowledgeable in disability discrimination.
I wish you the best of luck.
Pedersen Heck McQueen, APLC is an employee rights law firm assisting employees in all Southern California counties.
This answer should not be construed to create any attorney-client relationship. Such a relationship can be formed only through the mutual execution of an attorney-client agreement. The answer given is based on the extremely limited facts provided and the proper course of action might change significantly with the introduction of other facts. All who read this answer should not rely on the answer to govern their conduct. Please seek the advice of competent counsel after disclosing all facts to that attorney. This answer is intended for California residents only. The answering party is only licensed to practice in the State of California.