Anyone have any answers for me

Hi Im a. 20 year old male and I smoke ab a pack a day sometimes more. I know I need to quit and I pan on it soon. My question is that for the last year now I get a shape pain in my heart. Especcialy when I lift some thing heavy upstairs or anything with strain on me. Also I cough alot and recently I have alot of mucus Wichita I normally have abut more and I can feel it going down my throat. And I have something in my throat that is in the back. It hurts when I swallow. Should I go to the doctor ab this. Any ideas what it could be or direct me who to ask. ( been smoking since I was 13/14)