Green/yellow reoccuring smelly mucus.. (sorry, gross)?

ever since a year ago, at least once every few months i cough up yellow/green mucus that smells terrible.. i'm a smoker also, but when it started i did not smoke. i have a history of having tonsil stones if that means anything. it's so terrible, everything i smell, smells bad.. i'm sick also, have been for a few days with a cold.. any ideas what this might be? thank you