I would file a motion for contempt for failure to follow the parenting plan. In your declaration, I would state that your days were changed by agreement and that you two followed the new schedule for however long. You will also want to state how the mother has kept you from the child or otherwise failed to follow the plan. Remember, you need to get an order to show cause signed and have the mother personally served with the motion and the order.
Sign up to receive a 5-part series of useful information and advice about child custody law.