Coughing up blood..what could this mean?

I've had a cough come and go the past couple months. Two days ago I had my first nosebleed I have ever had (I'm 19 years old). Yesterday I was coughing extremely hard and eventually there was blood mixed in with my mucus. I went to the doctor yesterday (a very crappy free campus clinic that often misdiagnoses). He told me I have bronchitis. I am uming he is right because I usually get bronchitis every year, but this doesn't feel like bronchitis. I want to know what else it could be.