I've been feeling more tired and have some coughing blood. When should I see the doctor?

Coughing blood. The most common cause of coughing up (a small amount) of blood is acute bronchitis, in which it will go away in 1-2 days. If coughing up blood persists longer than this, or if you are a smoker over the age of 50, or if you take a medication that predisposes to blood clots (eg., oral contraceptives), you should see a doctor.
Yes!!! Immediately. You must be evaluated by a physician with these type of symptoms.