By stopping tobacco chewing you have reduced your chances of oral cancer considerably. Since you have undergone checkup with a specialist, you should not go back for another checkup. You should see a psychiatrist if 1. If your worry about possibility of mouth cancer is dominating your thinking; remains your main preoccupation throughout the day and causes considerable mental distress on a day to day basis. and/or 2. If you have other symptoms such as sadness, difficulty with sleep and appetite, irritability, tiredness, lack of concentration, lack of confidence, guilt, loss of interest in life in general. Overall, you are living a healthier life by giving up tobacco. You should not worry. Avoid constantly checking signs of cancer, constantly reading about oral cancer or visiting doctors. I hope this answer is helpful.