i've missed a number of pills over the past month and i've been experiencing dark brown sometimes pink breakthough bleeding for two weeks. it started fairly light but its become very heavy and i haven't missed any other pills since it began. i'm finding it very frustrating as i've had sex with my partner on a regular basis and the test came back negative just before the bleeding began. i've also been experiencing some cramping and back pain in conjunction with very tender breasts. i hate not knowing what is wrong with me as i'm beginning to feel exhausted and very stressed