In case of high frenum attachment, frenectomy procedure is done. Your dentist must have performed laser or scalpel frenectomy procedure. Healing after laser frenectomy is faster as compared to scalpel frenectomy.  White yellow stuff on surgical site is not unusual and is normally because of death of surface cells. Oral microflora can grow on thee dead cells and can lead to infection. Bump on lips can be there because of infection or because of injury to the soft tissue. Without clinical examination, it is difficult to give definite diagnosis. You can visit your dentist for evaluation. By the time you visit a dentist, you can do warm saline rinses 3-4 times a day to keep the area clean. For more info on frenectomy procedure, visit…….   http://www.identalhub.com/article_types-and-techniques-of-frenectomy-84.aspx