Claims for Work Injuries are to be filed within 1 year of knowledge of the work injury.
IF YOU CAN PROVE you just now learned that your condition was related to your work, you should file the Employee Claim Form for Industrial Injury (i'll try to pop in the link).
Expect the District's Comp adjuster to deny the claim.
Then you get ready to PROVE (1) you just recently 'learned' the injury was work-related, then (2) it was the work that caused this disability.
This is going to be tricky because I'll bet you dollars-to-donuts the private disability application you signed contained a promise that the you believed the disability was NOT at all related to employment.
One reason the District's Adjusting company can deny the claim is because you are no longer employed at the district... exceptions to the rule are medical records specifying that you reported A WORK INJURY to the doctor before leaving the employment...not just that you told the doc about back pain, but that you told the doc about WORK INJURYING YOUR BACK prior to leaving the district...
If your medical records contain Chart Notes indicating you knew or the physician advised you back in 2009 or 2010 that the Injury was work-related, the Statute of Limitations is a big problem.
But, as Mr. Borah notes, you've got little to lose (except perhaps your time and privacy).
Let's start by asking, "What do you have to lose by filing a workers' comp claim at this time?" The worst that can happen is that they'll say "No." The best that can happen is that they'll say "O.K." and give you benefits. So why not try?
There is a statute of limitations on making a workers' comp claim in California....one year. One year from the date of injury or one year from the date you knew you were injured, or one year from the date you found out it was work related. Sounds like you're still within the one year.
There is a prohibition against post-termination claims. Are you still working for the same employer? If not, any claim would now be post-termination. The three major exceptions to that rule are if the injury is cumulative trauma, ie. on-going wear and tear rather than a specific traumatic injury or if the employer knew about the injury before termination or if you received treatment for the injury before termination. Again, sounds like you're going to fall within one of the exceptions so you should be O.K.
I would expect the w.c. insurance company to deny your claim citing statute of limitations and/or post-termination claim. If that happens, get to a good w.c. attorney right away.
You may even want to consult with one before filing your claim. There are some great w.c. attorneys in the valley. Find a good one here at www.avvo.com or at www.caaa.org. CAAA is the association for attorneys here in California who represent injured workers. Or you can call me for a referral. Good luck.