Mucus in the stool is a sign of intestinal injury, most often either from a passing virus (in which case it would appear suddenly, and go away within a week or two) or from food intolerance. Blood in the stool may mean that the irritation to the gut is getting worse. I would take this very seriously, and work on finding the cause. The most usual cause of these symptoms in a breastfed baby (if they've lasted too long to be a virus) would be casein intolerance-- the protein in cow's milk. The other common cause is soy protein.
it can take a while for the offending proteins to clear your system, and for his intestine to heal. I would wait two or three weeks before deciding it isn't working, and looking for another cause. I myself, though, would be consulting with a knowledgeable health care professional, too, just because sometimes we as parents miss things that a health care provider might pick up on.
The green poop from oversupply isn't usually accompanied by blood and mucus, so that wouldn't be my first thought in this case.
My son was casein-intolerant, and still is allergic to soy. He started bleeding early-- at about a week old. By 18 months, he'd outgrown the problems with dairy. I'm so glad I found out what was wrong, and that we could deal with it. Giving up dairy was hard, but it got easier once I started getting used to it. After a few weeks, it became second-nature. Be careful to watch out for hidden dairy-derived ingredients in packaged foods, though. They can hide out under a lot of names.