Please help! What is this?!

My son has been sick with what I'm assuming is a bad cold for about 4 days now. He's been puking for a couple weeks at least once a day (not a lot but definitely more than spit up). He's always had issues with an itchy red dry face. So he scratches. It's spread to his neck. He  ended up scratching inside of his ear and his ear was covered in blood. Anyways. After he puked on me today I noticed he has a weird rash all over his back. It's not dry or scaly. It's just red and blotchy. What could this be?!