Son has infection under tongue, white, ?crooked?, frendelum...some sores, rest of mouth has no visible discoloration/infection.

Possible viral ...: Tongue , oral mucosa - inflammation - could be either viral ( as herpes - cold sores") or fungal as " oral thrush' . Sometime bacterial but wonder tongue uncommon ( unless injured) .For relieve recommend arm water with salt gargle and rinses. Liquid bland diet. If he has severe pain or fever , swollen glands.. he should be seen by doctor. Mild discomfort can be also relieve day ibuprofen ,tylenol