Is It Ok To Have Black Mucus In Your Period Can Anybody Tell Me Why??

Can anybody tell me why?? - is it ok to have black mucus in your period

ok my period was due on Saturday or Sunday and have a pain in my stomach as Senior ivebeen agitation be getting chest pain, and sometimes all day and especially around the abdomen is swollen and I I think I can not suck hard! Ive had a bit of wind and constipation, and now tonight, when I went into the bathroom, my stools are black with a orders of mucus that someone knows what is going on pls?