Additional Study Information: In this research study we want to learn more about a potential new therapy for pain associated with endometriosis. We want to determine if a non-hormonal medication, cabergoline, will help patients with endometriosis. Cabergoline is a medication that is approved by the Food and Drug Administration (FDA) for treatment of other medical conditions. In this study, the use of cabergoline is investigational. This means the drug is not approved by the FDA for the treatment of endometriosis. Cabergoline is a dopamine receptor agonist. Cabergoline binds to and stimulates specific chemical receptors on our cells that respond to dopamine, a chemical your body uses to help cells communicate with each other. Studies of these types of drugs show that cabergoline may help to prevent endometriosis lesions from growing.