What you were saying about your dog licking your blood, I know why.
Dogs have a tendency to like saltly things. The blood has a salty tang to it, which attracts your dog to lick it! He wants to know what that red thing is so he licks it. Long story short, he likes the taste if that salty stuff.
Do not let our dog do this. It could give him or you sickness and it could transmit things from you to him or visa versa.