You can most certainly still file a wage claim against your employer for failure to pay you wages that you actually worked.
In addition to the amount of wages, you would also be owed liquidated damages (an amount equal to the wages you didn't receive) and a day's pages per day you worked without receiving the money for your work.
You can file a wage claim using the information available online here:
It is important to note that you are protected from retaliation for filing a wage claim, and any additional retaliation that you face would give rise to an additional cause of action for wrongful termination and/or retaliation in violation of public policy.
Also, currently, you also have a cause of action against your employer for retaliation in violation of public policy for retaliating against you for complaining about the employer's illegal practices, including requiring you to work off the clock on Saturdays for any length of time.
If you are appropriately classified as a salaried employee currently, your employer is free to require you to work Saturdays now, but your employer may just be trying to get around paying you overtime and additional wages by making you 'salaried.'
Could you tell me what your primary job responsibilities are and whether you supervise any employees?