What could this be????

Last summer I was diagnosed with pleurisy (sp?) Anyways, I was given naproxen and a steroid to clear it up I stopped smoking and it got better, but now I woke up this morning and when i coughed it felt like the same thing it isn't a constant pain and it seems to only hurt when I exhale and in my back on my left side... What could this be? I also woke up with a little bit of a cough as well...