what causes a metallic taste in the mouth?
 Allergies, Sometimes our normal sense of taste can temporarily change, causing a metallic taste in the mouth.   Many systemic diseases including cancer, The gums tend to bleed after you brush or floss your teeth, and the blood in your mouth, hyperparathyroidism, renal failure, diabetes, Sjögren's syndrome, sarcoidosis, amyloidosis, vitamin B-12 deficiency and zinc deficiency. 