Blood in mouth

For the past 3-4 months I have been bringing up blood to my mouth. I am not vomitting it up, it just is there at times. When I spit it out it is not totally red, but a redish pink (deluted blood in spit i take it).  The only time it has been rred as blood was last week. After i had spit out my spit and blood mixture I cleared my throat, as if I had phlem to bring up, and a drop of blood came flying up. It was about the size of an eraser on the end of a pencil, so nothing too big. But since it has been occuring for so long I have goe to the doctor and am going to have an endoscopy performed on me in July. I have also been experiencing chest pain on the left side since before the blood problem starrted and have been wondering if the two arre related. I have seen a cardiologist and have had my heart ruled out so I was wondering if it could possibly be my lungs, or maybe an ulcer. If anyone has experienced something like this or knows anything about symptoms like these any input would be greatly appreciated. I am 22 years old. I am moderatley overweight 245lbs. Again I just want to reitterate that the blood is just there all of a sudden. I dont cough it up and i dont vomit it up. Its just there. I believe it is comming from my esophagus because as i said before once i spit out whatever is in my moth. I can bring morre up by clearing my throat. Again any input would be awesome.

thanks

Larshy

[boron]

Pinkish (froathy??) blood in the mouth and left thoracic pain may speak for the lesion in left lung or for embolus in a small pulmonary artery. Have you already had an x-ray of the chest?
On the other hand, if you don't cough, it my be from the throat or esophagus. But this blood would be obviously red.

Blood from the stomach would be black.