It sounds like you are experiencing a cold sores or oral herpes on your lip.
Appearance of cluster of blisters is always preceded with sensations of pain, burning, tingling, or itching.
These blisters break down rapidly and in a few days later, they become crusted or scabbed and appear drier and more yellow.
The complete duration of symptoms and signs is usually 2-3 weeks.
Oral herpes is easily spread by direct exposure to saliva or even from droplets in breath.
Transmission most often occurs through close personal contact, such as kissing. In addition, because HSV-1 can be passed in saliva, people should also avoid sharing toothbrushes or eating utensils with an infected person (even person without visible sores is infective since the virus is still shedding in saliva).