Oral pigmentation along with redness.

Initially it started in the right BM, now in left also it's there and increasing. I don't have issue with the pigmentation but the mouth feels weird, the area where pigmentation has occurred feels patchy/rough.. i have been prescribed caziq, kenacort and also dologel ct, steroid creams do help them reduce but when i stop it, the redness as you can see comes up again and later slowly it turns dark patch as seen. I have impacted wisdom tooth yes, going to get them extracted on Saturday, but in left side I already had wisdom tooth since 1-2 years but this never happened... I am just afraid that it will turn cancerous, i had physical checkups and doctors saying its fine but still i am worried as its increasing. Also I saw under top lip also this reaction is starting to come up(very small but yes its started)... Please help. Also could biopsy pinpoint the exact cause? I might ask my doctor to do that during the extraction... please explain this condition