Hi, I quit smoking marijuana about a week and a half ago, I have been smoking it regularly for 9 months on two separate occasions I had a severe cough from smoking too much and a little streak of blood came out, now since I quit I don't cough or anything my mucus is clear but occasionally when I hock(not cough) out mucus there are some black spots is it serious?

Nope. When you inhale smoke, from pot, tobacco, wood, etc, or coal dust or what not, you will get ash residue and the like in your lungs as well as tar and other chemicals. Your lungs have a lot of little cells call cillia on the inside. The primary function of these is to move mucus from the lungs, which will have impurities like dust and pollen, into your esophagus so that you can swallow and digest it. You wouldn't believe how much snot you actually digest. The black flecks and the like is your lungs trying to clean itself out. Since there has been a large amount of pollutants in your lungs, there will be a large about of mucus, and your body is going to be a little snotty for a while until things get back to a level of normal/expected.

The blood from coughing. There could be several reasons for that. I couldn't say for sure. Might be anything from an ulcer cause from smoking to REALLY bad acid reflux, to cancer, or anyone one of a number of things. That you should get checked out. Chances are it will heal up on it's own but it is hard to say what caused it. If you do talk to your doctor be COMPLETELY honest with him about your drug use. He can't turn you in and will suggest what you can do to get things back on track. If you're not honest he won't be able to properly diagnose you. That would be worse.