Hi A Few Days Ago I Had A Small.pain In

Hi a few days ago I had a small.pain in my chest/heart lasted for about 10.-15 mins, the next day I had the same pain but much worse it felt like I had a knife being pushed into my chest from the left side when I breath in. When I breath out it feels like the knife is being twisted, my breathing got shotter and shallow. This lasted for some time I had a pain going up my neck,left side and along my jaw,and up the back of the neck, I had a pain in my shoulder left side then a numbness down the arm and pins and needles in my hand. This eased after a while. Now if I do something simple like jog 20 paces with a 2 year old I get very short of breath and a pain in my chest left side. I've been told I go chalk white when I have pain, I can now hear a popping sound when laying on my left side at about half breath out feels like being flicked from the inside. I am a heavy smoker. Have always been fit and strong and able to work hard for long hours doing strenuous manual work. I used to walk between 15 and 20 miles a day while working and have never had a problem. I am slow and lethargic now get light headed have no appetite vision sometimes goes blurred, any thoughts would be great thanks Ewen.