Border of lip fading away and im only 17! please help!

I have consantly suffered from cold sores which has resulted with some scaring on my lips, The scarring has removed some areas of the pigment from areas on my lips were i had the sores.

But around 3 or 4 weeks ago on my left upper lip there is an area about 1 centimeter in size right along the border of my lip, this area is thin and is lossing color for a reason that i can not figure out. You can faintly see the distict line were the pigment should be, also when i squeeze my lips together i can see that this area there is white normal skin tone where there should be red/pinkish pigment. I have also been wearing a retainer that i recently noticed is pokin above the area where the actual depigmentation is occuring. There is a feeling of tingling sensation in the area where there is no pigment color also. I have also been trying to keep my lips moisturized but this seems to do nothing to bring the pigment back in that area... This is causing me alot of self-consciencness, and worrying. So please help!

Could there be a correlation between the retainer and the loss of pigment? I am worried that it will stay like this forever, What treatments can be done to reverse this??? or what is this?!! Any help would be greatly appreciated !