Hi.. Can understand your concern.. As per your complain the bump inside your mouth can be associated with the allergy and it can be an outcome of the allergic reaction causing inflammation and lump formation.. If it is allergic in nature it will resolve slowly by itself. You should avoid consuming the allergic food product. Other reason can be formation of BLOOD BLISTER which occur due to rupture of small blood vessels caused by injury to the inner side of lip caused by lip biting or any other trauma. It causes spillage of blood from ruptured vessel into the soft tissue and appears as a dark lump.It mostly resolves by itself. One other reason can be damage to the minor salivary gland and its ducts due to injury causing spillage of the mucus into soft tissues and forming a lump known as MUCOCELE .. It also mostly ruptures itself by discharging its fluids into the mouth. Larger mucoceles may require excision surgically or by use of laser. I would suggest you to wait and watch for a week and if the bump starts resolving its fine or else if it increases in size or there is pain or if it does not resolve you should see a doctor to get ruled out for other less common conditions like Melanoma. Hope your query is solved.. Thanks and regards.. Dr.Honey Nandwani Arora.