When you have a metallic taste in your mouth you can drink acidic drinks like lemonade or limeade which will help get rid of the metallic taste.
If the metallic taste comes back then it could be some medical condition that needs to be checked out by a doctor but sometimes a metallic taste can happen due to poor oral hygiene, problems with the nerve system, ear infections or upper respiratory infections including sinusitis etc.
Some other things such as gingivitis, periodontitis can be a cause of metallic taste in your mouth too.
Also try brushing your tongue with some toothpaste or gargle with some Apple Cider Vinegar because Apple Cider Vinegar can help fight infections and clean bacteria out of your mouth so the metallic taste should go away.