You poor thing! Must be quite painful right? Well done for being so brave and carrying on.
When I bf my first son it was very painful, so I made sure I used lanolin creams and even used nipple shields when they were very sore so they'd have time to heal. Make sure your nipples get lots of air so they have time to dry up and heal, also that they remain clean.
I dont't think there is anything wrong with blood in the milk. He'd tell you if there was by coughing up his feed. But think the nipple shields would help here by making sure the milk and blood dont't mix. Hope that helps and lots of luck xxxxxx