Help! i have no idea why but ive recently had problems with puking?

ok so i rarely puke i usually have to get a serious case of the flu. and ive never had eating disorders theres 0 chance of being pregnant and i have hardly any gag reflex so its not any of that. but for some reason last week i was out having a cigarette [and yes i know its bad for me but ive been a chainsmoker for a couple years now and didnt even puke with m first one] and before i went inside i started to feel kinda woozy and all of a sudden i projectile puked. after i was done getting rid of the pepsi and stomach acid i felt a bit weak but 5 min later i was back to normal. no fever or other signs of sickness either. then this morning it happened again when i finished getting ready and i didnt even smoke this time. once again i was fine before i puked and fine afterwards. ive never had any problems like this before and have no idea what the cause would be since im not actually sick. an ideas people?