What Causes Throat Pain, Chest Tightness And Shortness Of Breath?

I have been experiencing shortness of breath, tightness in chest and a somewhat hoarseness or catch in my throat for about 3 weeks. Some pain in my throat and have been very tired. I am a smoker and have been under a lot of stress in the past month or so. I am 40 year old male. The pain in my throat is different than the pain associated with a common cold...it is lower almost into the chest.