Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain sudden onset of pain in my frenulum under tongue along with eruption of a white blister seems most probably be due to eruption of an Apthous ulcer or a canker sore.. It can also be a traumatic ulcer caused due to injury to the frenulum area with some hard food.. Nothing to worry as it will resolve in a period of a week or even less.. The medications that you are taking that is peroxide gargles, anti-inflammatory painkiller Ibuprofen and Lidocaine solution that is numbing gel and will relieve the pain by numbing the area.. Along with it you should also take Vitamin B complex capsule for a week. You should take a soft and bland diet.. Avoid spicy and hard foods.. Avoid toughing the area again and again.. Do cool compresses or rinse with cool water to reduce inflammation and swelling.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.