I've Had Very Low Flow, Black Menstrual Blood For 3

I've had very low flow, black menstrual blood for 3 days now and have not started my period this month. Just recently, I have been gagging in the morning through out the after noon at random times. I have pain in my stomach but that is normal to me since I am a stressful person. I was told a year ago I had a 2cm size cyst in my uterus but was unable to follow up due to my finances. My last pregnancy about 3 years ago was a very difficult pregnancy. I was healthy but my child was not. He passed away shortly after he was born. I'm not sure if that is all tied in to my current issue.