Last month I developed a cold but then it became pneumonia after going to school in the rain. Now, this occurred a few weeks ago. I went to the hospital and was prescribed antibiotics and other things for it. It made me feel better, however, after using up all of them, I noticed that I am still coughing up mucus/phlegm and I hear a slight vibrating sound in my lungs when I lay down. I need to know, is this just residual stuf that my body is getting rid of??