Yooo new here and have question about chest pain

So im 18 and ive been smoking for about 4 years, several months ago i started getting some pretty severe chest pain (what i would describe to be my heart) every time i lit up. I ignored it for a few weeks and then i had the worst attack ever, my heart must have been beating 200 bpm and it felt like someone was stabbing my heart (honestly though about calling 911 cuz i thought it was a heart attack) . I just relaxed and eventually it went away but ever since that day i stopped smoking and thought i should try to be a bit healthier. i waited a good 2 months and i thought to myself "you know i havent smoked in a long time and ive been eating healthier and exercising so i should try and smoke again" i took 1 fat rip from a pipe and instantly felt really good, i ate some food and sat down to play some MW2 and got that heart pain again. I dont get this pain when i smoke cigs or when i drink only when i blaze and i really dont wanna stop smoking, does anyone know why i would be getting this pain or have had any similar experiences. (oh and ive been to the doctor and they said nothing is wrong with me)