The accessory navicular syndrome can be debilitating and cause you a lot of pain. In this case, you may have to restrict activities. You may also need to be in soft shoes and provide good cushioning for your feet, at least until the foot heals. If you see the symptoms persisting, then you can get a specially made shoe.
If you experience severe symptoms, surgery may be an option. The surgery is to remove a bony growth. You may also need to use other treatments such as medication or by immobilizing the area with a cast and then physical therapy.