Could it be a pulmonary embolism?

Hi there, I've had a cough that pretty much came out of nowhere for a week or so now. I'm 21, have no other symptoms, don't suffer asthma or allergies. There's no phlegm with the cough, is just irritating and constant. I know I'm most likely over reacting, but is there any chance it could be a pulmonary embolism? I'm going to see a doctor as soon as I can get the money for it, but until then I have to sit and worry. Any reuring advice would be appreciated.