I have black pigmentation on hard palate. it first appeared two weeks ago and appears to be getting larger. i also have a metallic sensation in area.

Unknown lesion: It is impossible to diagnose these types of situations over the internet. We are only able to make some educated guesses which in reality will do you no good and possible harm.You need to be seen by a local dentist (or Oral Surgeon) for a one on one clinical exam. Regardless, any lesion that lasts over two weeks demands a definitive diagnosis.