Hi Dear, Welcome to HCM. Understanding your concern. as per your query you have symptoms of redness and swollen bump on top of lip. The symptoms you mention in your query pointing towards a condition called stomatitis.There are number of factors tah can cause stomatitis like irritation of mucosa as in case of mouth breather occur due to dry mouth,nutritional deficiency like vitamin B12 and folic acid and food allergy.It can also caused by herpes virus particularly type2. Need not to worry. Sometimes these spots go away themselves in 7-10 days. I would suggest you avoid hot and spicy food or acidic drinks (citrus fruits),drink plenty of water to maintain hydration of body ,rinse his/her mouth with warm saline water and maintain proper oral hygiene by brushing twice a day. If condition persists or get worse then consult dentist or pedodontist for proper examination and to rule out other conditions .Doctor may prescribe oral antibiotics ,saliva substitute,lidocain gel in case of burning sensation or oral/topical antiviral in case of viral infection. Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari