Formally,you should be brave. It is right time to leave smoking not suddenly use 1/2 packet/week upto 1month.And stop immediately followed by your family doctor he/she will give best support as well as best suggestions. be brave all is well
The first thing you do when you cough up blood is to go see a doctor to get some tests done. You are way too young for cancer due to smoking. However, there are many other reasons for cancer. Do not put this off!
Accept this as a sign and do your self a favor and quit smoking while you are young. Smoking is the most difficult addiction to get rid of compared to weed, crack and or heroine. At 16 it cannot be an addiction yet.