I am 23 years old and have had asthma since I was born, and smoked a little when I was younger. For the past year I have had a dull, annoying pain in my left lung. I have had an xray but nothing was seen. I cough up regular mucas stuff with a little bit of stuff that looks like dirt, mixed in with it. I do smoke medical marijuana, but nothing else. I just wonder what it could be?????? Thank you anyone who can help me.......