You can go to one of the overnight emergency care centers. This is particularly useful if you think you have a broken bone after hours, or if you need stitches or if you have a minor issue that needs medical attention but isn't life threatening.
Your two final options are to go to the emergency room to be seen by an ER doctor like Josyann Abisaab or to call an ambulance. An ambulance should only be called if you feel that you need immediate assistance and that you'll need assistance on the way to the hospital.
Hopefully, with these options in mind, you'll be able to make the right decision when the time comes and someone needs attention in your house.