A metallic taste in the mouth can be caused by many things including infections, pregnancy, gum disease, inadequate water intake, kidney problems, medications or inhaled substances and usually is not a serious cause for concern.
Too high a dose of iodine has been reported in some people to cause a metallic taste in the mouth but this is rare. You can decrease the amount of iodine you are using per day and see if this helps.
Rinsing your mouth with about 1/4 tsp. of sodium bicarbonate in a glass of water once or twice a day for awhile should also help to reduce this taste along with taking care of any underlying problem that may be detected by a qualified health care provider.