I've had a cough for about 3 days now pretty much none stop. i just coughed up blood. what does this mean?

See a doctor: Coughing up blood is not something to take lightly. It can mean a number of things, but you should seek medical attention right away so they can determine the cause.

Hemoptysis....: The most common cause of coughing blood, called hemoptysis, is bronchitis. However, this symptom always needs to be seen by a doctor because malignancy can also lead to hemoptysis. So, see your doctor asap. If you smoke, you need to quit today to decrease airway inflammation.