Hi.. Thanks for the query.. I have gone through your query and can understand your concerns.. As per your complain it looks.like a tiny bump along with redness is due to APTHOUS ULCER which is causing you the eruption of a painful lump on lower labial frenulum.. It can be caused commonly due to causes like toothbrush trauma, eating something very hard, spicy and sour foods, burning with hot liquid or chemicals like mouthwash, some other forms of traumatic injury etc.. For apthous ulcer you can do warm saline gargles Gargles with 1:1 solution of benadryl and milk of magnesia can help.. Apply numbing gel over the sore for relief from pain especially during eating.. Take a Vitamin B complex for a week.. Avoid spicy, sour and acidic foods.. Apply cool packs or suck ice lollies.. Hope this information helps.. Thanks and regards.. Dr.Honey Nandwani Arora.