Hello, thank you for consulting with us. As you are mentioning that you have noticed red patch towards the back side of tongue there can be many options for this
- It can be just papilla of tongue which you must have noticed
- It can be trauma or burn from any food if it than it will be healed in few days
- It can also be an ulcer which will also heal after few days
It is better that you should visit your nearby dentist
for examination of the lesion.