A doctor doesn't need to decide if it's work related. You need to report it to your employer. If they refuse to submit a claim, then you contact the WC board and self submit. You can have an injury that is over a period of time. Whether or not you've let it go so long and treated it as if it was not a work injury...

Attorneys in CA are being much more picky about clients right now.

You always have the option of filing for SSDI if your condition reaches the point where you'll be unable to return to work.