What Causes Loss Of Sense Of Taste?

I have lost my sense of taste over the past week . I have been depressed fpr 6 months and not eating well but this loss of taste happened rather quickly. Chocolate especially has a bitter metallic taste and I cant tell what liquids are. Milk or juice etc all have a bitter metal taste. I take Effexor and 2 medications for High BP but have been on these for a couple of years. Other than that I am in excellent health, slim, active and non smoker . Thankyou