What Causes Red Small Patches Of Bumps All Over The Lips ?

Hi, My name is Kryssy. I'm 18 years old. I seem to have a problem with my mouth. I get small patches of bumps all over my lips. They get really red and swollen and peel. Its very painful and it itchs. I've been to the doctor before and she said it could be from the sun, but i've noticed this occurs through out the day and at night time. She prescribed valtrex and it seemed to help out some. The only thing managing it okay now is carmex. I've never given oral sex to anyone to have that type of herpe. I don't have anything on my tongue, gum, etc...just on my lips. Please help?