What Causes Metallic Taste In Mouth?

Last night I had a sudden on set of a metallic taste in my mouth. When I woke up this morning my upper back were sore. Still have both symptoms. Back pain may be partially from assisting fallen skiers get back up, I had a large student 2 days ago. That does not explain the metallic taste. I am also a life guard at an indoor pool facility. Chemicals had to be hand added to 1 body of water while I was working last night. I was in the pool area but not handling the chemicals.