Sean,
There is no "national" registry of CNA's. No such thing as nationally certified...
and don't let anyone tell you otherwise.
The CNA role was regulated under the OBRA '87 laws. Nursing homes can only employ aides who have met certain training criteria- and the laws vary by state but basically aides must attend classes with certain topics covered; number of hours in class are also mandated. Continuing education hours are mandated. OBRA added regulation to nursing home aides because of the high rate of abuse and neglect that was happening back before the laws went into effect. The laws only cover nursing homes. They do not include hospitals, assisted living facilities, hospices, free standing clinics.
It sounds to me like you're an OR Tech of some sort. (There is a national registry of OR TECHS...I wonder if that nurse is confused?) Since it's been SO long since you were in any training for CNA, you'll probably need to start over: Take a class, take the state test and pass it, then get a job a CNA. I would wait until you get to Cali, then take a class out there and take the Cali test, get the certification and so on. You can do it now in NY, but you'll have to pay extra once in CA for reciprocity- and they may not accept NY's standards which means you'd have to take MORE classes.
After you've gained employment, you can be reimbursed the costs of the CNA classes only if your employer is a nursing home. By law, they must reimburse you those costs- they get the money from the federal government. Most nursing homes DON'T LIKE TO BROADCAST this federally mandated rule- but it is the law. They get MONEY to hire CNA's! THAT money belongs to the newly trained aides and not the nursing home...so fight for it. And don't be fooled by them telling you that they'll give you "free" training if you agree to work for them for a certain amount of time if you sign a contract. This is illegal. THEY can require that you give back prorated sums of money they invested in you for the "free" training however. SO be careful.