I had the metallic taste in my mouth and I used detox foot pads (www.purifyyourbody.com) and that helped immensely. www.bodypurenow.com also sells them. Maybe you should try them to see if they will help you?
Do you have any other work done on your teeth? Like root canals or crowns? They use metal sometimes for those, metal that may not be the best for your mouth.