Hello,
The red spot under your tongue appears to be an ulcer, possibly caused by irritation, heat, or trauma. Can be secondary to viral infection also. Given your history of smoking, it is important to monitor it closely.
Next Steps
If the lesion does not improve within few days, or if you notice more spots, pain, or changes in size/appearance, please consult an ENT specialist for a proper evaluation.
Health Tips
Here’s what you can do for now:
Avoid hot fluids, spicy or acidic foods.
Drink plenty of water and stay hydrated.
Reduce or stop smoking and alcohol as they can delay healing.
Maintain good oral hygiene.
Take care.