Good morning, I am a 16 year old male, 150 pounds, 5 11 and since this past friday, Febuary 22, 2013, I have had blood in my stool 2 out of three times that I have gone to the restroom. I smoked marijuana for the first time friday evening with my friends. I took 3 hits, each time holding it in my lungs for approx. 4 secs, then releasing it. I also smoked 2 cigarettes, them also being the first I have ever smoked. I am very concerned about why I have blood in my feces, and I would really like to get this problem solved. Any help would be greatly appreciated.