Please don't wait for the soreness or ulcers to appear in that area, because that would indicate that the ongoing damage has reached another level. What type of tobacco product who are you using and with what frequency and for what duration???? How long has it been that you have quit that habit???? Mostly these habits are chronic, so the damage that occurs due to these habits does not die out immediately after the habit is stopped. Going by the description that you have mentioned, it seems you have clinical signs of leukoplakia and it needs to be evaluated clinically to determine its grade and histologic assessment is required to determine the stage of the disease. Without having a clinical look at the case, I can tell you that this result can be in terms of a simple keratosis to even a precancerous change. Please do not delay your visit to the dentist. The right treatment can be instituted only after the right diagnosis has been established. Alternatively you can post the clinical pictures of your lesion on Practo for an online consultation with a specialist. Regards.