My 15 yr old daughter said that the gum on her right second premolar tooth is sensitive and she noticed a small dark/black spot on the gum near to her tooth. it feels like tooth decay on her gum but the tooth feels fine. is this a worry? what is it?

Hard to say: To alleviate any concerns you should take your daughter to a dentist and have that area examined. Very possibly it is a remnant of the root of the primary tooth that was there before the premolar erupted. If so, it should be removed.

Needs examination: Small black spot/sensitivity could be anything from a cavity, a baby tooth root tip, trauma to the gum tissue, a burn, or so many other possibilities. Please have your daughter examined by your Dentist to determine the cause, and the appropriate treatment, for the lesion.