Is it like a metallic taste? I don't know what poison tastes like so i can't imagine

if it is a metallic taste check your throat ( get a flashlight and stand in front of a mirror) by the dangly bit (uvula) are there red, slightly puffy lumps (tonsils) ? Or does your throat look really red? I had the same taste ever since I was 4 and it progressed into tonsillitis and eventually I got them taken out (after 10 years of waiting) if not then see your doctor, you may have a bacterial infection
Hope it helps