blood in my stool ?! ER ? or should I leave it .

A few days prior to me worrying I noticed I had black stool... and then starting on Friday night , I had pretty bad stomach pain . It started in my actual stomach and felt like a burning sensation but slowly started to move it's way down and burn in my lower abdomen . It almost felt like when you are starving and haven't eaten in a while . So I though that it was probably just hunger mixed with gas and ignored it . But when I got home I noticed a streak in my panties so I wiped and saw dark black/burgundy blood coming out of my butt ... I'm no where near starting my period so it isn't that. I also have been noticing my stool has stayed this dark colour , up until today . It still has spots of dark , earlier it was half black half normal and then just now it was normal with big spots of black . I haven't noticed any bleeding when I wipe anymore except after a bowel movement . It's not a hemorrhoid because the blood is dark not bright red . I do get some bad cramping pains in my lower abdomen and have had them for a while now ... maybe a month . My family thinks I should go to the emergency room next time I get the pain and black stool . I think since it's becoming less that it's probably getting better on its own . I don't expect you to know what it is but do you think it could wait until I can see a doctor , or should I go to the hospital in the case I'm bleeding internally ?