You woke up with nausea and spitting up blood-What can that be?

you are bleeding anywhere from your nasal passages to your stomach--blood gives you nausea & causes vomiting. Regardless, you need to go see a doctor. If it is a LOT of blood and vomiting, obviously go to the ER. It could be a nosebleed that was able to empty into your stomach overnight, then it might be an esophageal varicosity that has ruptured, or then it could be a gastric ulcer. Your doc will need a lot more history, though--like whether or not you are a smoker, drinker