How do I know if I have herpes?! How can I cure this thing on my lip?!?

This actually is a type of Herpes commonly known as a cold sore. There are over the counter creams for these. Generally the outbreak is caused by sun exposure. You can pass this on to other people when the sore is "weeping'. Have someone bring you one of these products and start using it. You can take Tylenol or Aspirin for the pain. With treatment this will clear within 7 to 10 days sooner if you limit your sun exposure.