Pink raised line under bottom lip

We originally thought this problem was dermatological, but were told it's actually something you should see a dentist about. In November 2011, I had occasional itching at the edge of my bottom lip. In December, pink lines appeared on either side under my bottom lip. Within a couple of weeks, the lines extended all the way across my lip to form one line, and the line became slightly raised. It's currently about 1/16 of an inch wide. I still get occasional itching and can see a few tiny red dots where the lines originated on the edges.

I was prescribed Nystatin-Triamcinolone ointment applied 4 times a day for a week. This lightened the line somewhat and a couple of pinhead-sized spots returned to normal, but there was no further improvement.

What could this be? I've been off yeast for a month and a half, but it hasn't made any difference. I have a picture, but there doesn't seem to be anywhere to put it. Thank you so much for any help you can give.