clear mucus with brown spots and Coughing up blood

Hi, i first coughed up blood streaked clear mucus in September and was given a course of antibiotics. it stopped me coughing the mucus but did not stop the cough or pains. i have been to the dr several times who say they cannot hear any problems with my lungs or chest and have given me a salbutamol inhaler to help with the chest tightness. yesterday i coughed up some clear mucus with brown spots in it and then proceeded to spit up blood. I have suffered with rib and shoulder blade pain for some time and yesterday it hurt to even breathe or cough. dr sent me for a chest x ray and gave me more antibiotics. it is going to take a week for my chest x ray to find its way back to my dr and i am really worried this is something serious. Has anyone else had similar symptoms?? Please help