U to have cancer is least chance.
Reason 1. You are too young
Reason 2. You are not chronic smoker
The thing what u have below your tongue is an ulcer,
Mostly due to stress, may be that was the reason u started smoking.
Reduced your stress, take break
Next Steps
drink lot of water;
have fruits;
apply anesthetic gel like mucopain on it;
buy some B-complex, take one capsule per day;
meditation helps relieve stress.
Health Tips
send pics of this lesions. or
visit an oral medicine doctor nearby for accurate diagnosis