Umbilical cord bleeding after falling off?

first id like to say that im also asking my doctor about this right now. my son is 3 weeks and 2 days. this morning his cord had a tiny bit of blood on it and looked like it had come off just a little but it was still attached. the next time i changed his diaper the cord had come off and it was inside his shirt. i cleaned the little bit of blood off his belly and changed his diaper, this was a few hours ago. just a few minutes ago i went to change him again and he is still bleeding from his belly. its not dripping blood but its still noticably bleeding. im freaking out.. is something wrong? did it come off to early? its not supposed to bleed is it?