Hi.. Thanks for the query.. I have gone through your query and will try my level best to resolve it to the best of my experience.. As per your complain the sore on the side of your tongue can be a canker sore or an apthous ulcer that is causing you pain due to inflammation.. It can be due to any sharp cup of the tooth that is injuring the side of the tongue, tongue bite, trauma cause by toothbrush or chewing hard foods, burning with hot foods, eating plenty of sour or tart candies and other tart foods etc.. You need not to worry about it as it will be resolved gradually in a period of 5-7 days.. As of now to relieve pain you can apply numbing gel containing Lignocaine over it.. You can take Vitamin B complex for a week.. You can suck ice popsicles do cool water rinses.. Warm saline gargles and soda bicarb gargles can also help.. Take soft diet and avoid spicy and hard foods to prevent further irritation and inflammation that can cause pain.. Hope your query is resolved.. Regards.