Spot on lower lip?

I'm afraid of something that appeared on my lip about a month and a half to two months ago. I thought my lip just got sunburned but it never went away. My lower lip has turned dark all except for one bright pink spot. I thought it was because of my retin-a for my acne on maybe the anti-biotic I have been taking for my acne.

I have included a picture for further diagnosis. I'd like to know what I have if possible and how to treat it.

Thank you for your time.

[sarahm2009]

hi. i too have a dark lo0wer lip, but i dont have a bright pinki spot......my doctor said it was post-inflammatory hyperpigmenation and it takeas a while to get the colcor of my lips to go back to normal, it *****!

[ConcernedLL]

Did he say anything about the time frame?