Tongue problem

my girlfriend went to her dentist yesterday morning to have a couple teeth cavities filled.  When they injected her with Novocain she states that it hurt bad.  And ever since she has had some kind of nerve problems on the tip of the tongue.  Having a constant burnt tongue sensation.

Now the next morning there is a very visible spot where the pain is.  Its almost like a bruise looking circle that even goes a little to the under of the tongue.

Any ideas?  Thanks guys

[mammo]

I would have her go back to her dentist and tell him what happened and let him look at it.  I've never heard of enything like this.