Hi.. Thanks for the query.. Pain under the tongue can be due to causes like any traumatic injury caused by any hard or sharp foods, pain originating from salivary gland due to infection or blocked duct, swollen or infected lymph nodes, muscle pull etc.. So for confirmation of the exact cause a clinical examination, palpation of the area and if needed an x ray can be done. For now you can take painkillers, muscle relaxant and along with it take soft meals.. If there is swelling you can do cool compresses and avoid pressing the area again and again as it can exaggerate pain.. Hope this helps.. Regards.