The multiple nevi you experience might have appeared on their own, and not caused by any disease. You might want to visit your gynecologist to rule out possible gynecology problems and then visit a dermatologist for dermatoscopy.
Also, you might want to have in mind the fact that the nevi might sometimes be misdiagnosed local hyperpigmentation by non medical person. So you should not worry until the nevi are seen by a health care professional. But you should definitely pay a visit to one.