Hello, I would recommend you to see a general physician as greenish gray or clay colored stool indicate bile duct obstruction. It is unlikely that the contraceptive pill is causing the alteration in stool color, and pain in the ganglia. The underlying cause can be detected using diagnostic test like liver function test, ultrasound abdomen, and stool examination. In addition, it is better to get the ganglion examined by a doctor as a painful ganglion needs excision in most cases. You can even take an x-ray of neck to make sure the pain is from ganglion, and not due to problem of cervical vertebra. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Ayesha Shareef, General & Family Physician