I have a sore on my lip that's covered with a yellow crust and is weeping throughout the day. should i go been seen by a doctor?

Yes: dermatologic conditions are hard to discuss without seeing them. AND the yellow crust is a pretty typical description for a common infection that needs antibiotics.

Possible cold sore: It sounds like you have a cold sore, which is caused by the herpes virus. See you dentist or physician for proper diagnosis. If this is what you have there is no cure, but there are creams available to decrease the length of time that the lesions is present.