The workers' comp. laws in California prohibit "post-termination" claims. If you were terminated (laid-off) before making your claim, it can be denied. There are a couple of exceptions to the rule. The first is if the injury is due to what we call "cumulative truama" or on-going wear and tear. This sounds like what you are describing so you should be able to still make your claim. Another exception is if the employer knew about the injury before the termination. A third exception is if you were receiving treatment for the injury before the termination. I would expect the workers' comp. carrer to deny your case and you will then have an uphill battle with them to get it accepted.
While the case is on delay status for them to investigate, they have to pay up to $10,000 in medical bills for the injury. If you need treatment, get it quickly while it's still on delay. Once denied, it will be a while before you get that reversed (if ever) and you will be receiving no benefits while in a "denied" status.
This case is going to get very complicated very quickly. It is going to get denied. You will have the chance to get a medical second opinion, a Panel Qualfied Medical Examination. You should not request this PQME or go to it without first consuting an attorney. You should not have your statement or deposition taken without consulting an attorney. You should not sign anything for the insurance company without consulting an attorney. Find a good one here at www.avvo.com or at www.caaa.org. CAAA is the association for attorneys who represent injured workers here in California. There are some excellent attorneys in the Sacramento area. Good luck.
Generally, post-termination claims will be denied unless you received medical care for the work-related injury before you were terminated. The insurance carrier at the very least will delay your claim pending an investigation.
Always report injuries when they happen. It is illegal for an employer to terminate an employee on the basis of the employee's bringing a workers' compensation claim.