Hi, I had quite strong cold about 5 weeks ago. After the symptoms of cold (full nose , coughing sputum ) went away, I started to have dry cough. About 2 weeks ago I noticed a little blood in my saliva after once prolonged coughing. I went to doctor - he did X-ray of my chest, blood test, then I went to ORL doctor - he checked my throat. All results were negative. Now I do not cough but today I noticed again little blood in my saliva. Should I be worried?