Hello, Mini pill is the progestogen-only pill and it can make changes in the periods. Periods may be lighter, more frequent or may stop altogether. There can be bleeding between periods. Jelly like black discharge may be indicative of old blood that is coming out, it can also be indication of implantation bleeding. Get examined by a gynecologist and get required blood tests, test for pregnancy and ultrasonography of the uterus and fallopian tubes done to detect ectopic pregnancy, pregnancy or ovarian cysts. When taking the progestogen-only pill. The risk of developing fluid-filled sacs on your ovaries (ovarian cysts) is there. In the meantime, take antacids to get rid of abdominal pain and discomfort. Taking PPIs may be helpful. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician