When an ovarian cyst ruptures you may or not feel it. Depending on the size of the cyst it may not be painful and you won't feel anything at all. It may rupture during your menstrual, so you wouldn't notice a difference. However, sometimes they can enlarge and rupture causing pain, excessive bleeding and even nausea. If you are bleeding in a way that is not normal or have sudden pain in your pelvis area, you should contact your doctor.