I am 21 years old i am a smoker and i am on yaz birth control. a few hours ago i started having dull/slightly burning chest discomfort. now my throat feeling a little heavy. should i be concerned?

It is the best time to quit smoking and I know it is possible when you want to. The birth control hormones and smoking may increase chances of blood clot disease like deep venous thrombosis, pulmonary embolism, stroke and heart attack. I doubt that you have any of that; but smoking could also cause shortness of breadth from bronchitis and emphysema.

Low dose oral contraceptives like "Yaz" are unlikely to cause chest discomfort in a "21 yo", but check with your physician if symptoms continue. Smoking tobacco is addictive, and contributes to multiple disease entities, most of which shorten life expectancy.