Hi.. Thanks for the query.. A sharp tiny bit under the tongue on the middle of gland seems to be a salivary gland stone or a sialolith that might have formed in the duct of the salivary gland and it can even more common to occur after salivary gland infection.. I would suggest you to consult an Oral Physician and get evaluated and a thorough clinical evaluation and investigations like cross sectional x ray or MRI of the salivary gland can help in diagnosis and treatment can be planned accordingly... As of now you can apply numbing gel over it in case of pain.. Once the diagnosis is confirmed and in case if it is a stone the physician can try to remove it by pushing it manually towards the duct orifice.. If it is not removed manually a small incision/ cut can be given under local anaesthesia over the stone and removed.. Hope this helps.. Regards.