What Causes Vomiting While Smoking?

Hi. I don't know if it's the flu bug or because of smoking. Been smoking for 15 years and yesterday threw up 4 times. Once while I was smoking and another time right after I took a gravol pill. Do you know what it could be. I have never threw up while smoking before. I'm not coughing or anything like that and have smoked since I threw up and will admit don't feel 100% after smoking but at least not throwing up now.
I'm confused.
Thank you