What would cause a METALLIC taste in my mouth? I'm not on any new medications.

Maybe you are tasting blood. Blood has a metallic taste.

Touching something with DMSO in it or some other chemical solvent that can enter your body through the skin. If you have touched paint anytime recently that might do it. Also if you have bleeding gums or a very upset tummy. The upset tummy can cause bile to come up and that tastes metallic.

Mayo Clinic dental care specialist Alan Carr, D.M.D., and colleagues answer select questions from readers.
Answer
A metallic taste in the mouth is a fairly common problem — and usually not serious. Although you don't have actual taste buds that detect metals, the perception of the taste is described as "metallic."

A metallic taste can be due to many factors. But the most common causes of a metallic taste are:

Medications such as some antibiotics, prenatal vitamins and antidepressants, as well as drugs used to treat high blood pressure, rheumatoid arthritis and kidney stones
Oral problems, including oral infections such as gingivitis or periodontitis, tooth infections, and poor oral hygiene
Sometimes the cause of a metallic taste can't be determined. In many cases, the problem goes away on its own after several months or longer. Proper oral hygiene can help, including regularly brushing your teeth and brushing and scraping your tongue. Done properly, dental restorations — such as fillings and inlays — are rarely the cause a metallic taste.

Brushing your teeth too hard? Also if you've eaten something with alot of iron in it.

dehydration can cause it in my experience,also if you have not looked after your mouth recently.Sometimes cleaning your teeth isnt enough you may need to invest in a good oral mouthwash such as cordosil which should only be used for a limited period of time otherwise it will stain your teeth.

Arsnic poisining causes a metal taste in your mouth.

are you pregnant?

food poisoning from tainted seafood/shellfish, can cause metallic taste in your mouth


source: National institute of health
http://www.nlm.nih.gov/medlineplus/ency/article/002851.htm

Also, very good dental hygine.

Maybe you have an old filling in your tooth that needs re-doing.

Da Azian Boi is right, most often it's blood.
you may have a small cut or sore in your mouth or throat. It may also be your sinuses, if it lasts more then 3 days call your doctor on the phone and ask if you should come in. Some times a sinus infection can cause the taste of blood in your mouth, if this is what it is you should have it treated before you start a fever.

I had a metallic-cedar flavor in my mouth for several days before I was aware of the "hot spot" in my chest. Then it was obviously a virual situation in my lungs. No fever, no pleghm. Is this what's described as "walking pneumonia"? Compared to the bacterial pneumonia, I'll take this.