Bleeding, bald spot under neck

Okay I saw my cat kept scratching himself under his neck area and I thought maybe it was a tick. No, it was a bald, bleeding spot. No idea where he got it from, it didn't look like he was bitten, there were no teeth marks or any marks of any kind, just very red and bleeding skin. He's not allowed outside without me watching him sooo....ANY idea on what this could be?? A little nervous! He won't stop scratching it and I tied a little scarf around his neck to keep his nails from getting to it but it doesn't really work, lol. I put some neosporin on it with a Q-tip and it must hurt because he tries to get away when I touch it. I don't want to take him to the vet just yet, I'll watch it for a few days and hope that it heals on its own!

When was he last de-flead?

Are there black spots in the area? If so, it could be either fleas or feline acne, just for two possibilities.