Thanks for using the forum.
It sounds like you have a cold sore, but without examination I can't tell. If the area is red, painful, has drainage, is hot to the touch, you could have an infection and I would recommend that you see a doctor to have it checked out. If the area is irritated by a hot, dry climate, I recommend that you keep you lips moisturized with a lip balm. If you spend time outside you should look for a lip balm with SPF.
I hope this helps.
Cathy
Thought I could post a picture. There are a group of yellowish bubbles on my lip on the bottom right side