This might sound strange and it came from an alternative source. Lyme patients livers sometimes do not work properly, my husband's liver enzymes have never normalized since he got lyme eight years ago. Sometimes the liver will not rid your body of metal toxins such as mercury from teeth fillings. Anyway, this also can cause the metal taste in the mouth and you can do a detox for it. If it doesn't go away after you are off the meds, I'd try a metal detox.