Moldy=Bloody?

So I told my friend, the Biology grad student, about my black moldy vomit situation. He immediately told me that it wasn't mold, but in fact blood. According to him and also CNN.com when you vomit blood that has been in your stomach for a while it appears black or dark brown.
Possible causes are:
Peptic ulcers
Internal inflammation
or Cancer
Needless to say, I will be checking in to WSU Health and Wellness as soon as possible.