I am male, 21 years old. My weight 60kg, height 165. My problem has begun since August. I first have just tried to smoke a cigarette from June until August. Even though, i wasn't professional neither heavy smoker. I smoked around 2 cigarettes a week. When I smoked, I puff the smoke from my mouth, then I smell it instead of inhaling. So, during that period, I never experienced persistence cough, cold & flu, heart racing, vomiting, less of appetite. However, I played soccer, and I felt lightheadedness, and I could continue to play within seconds. Also, I was drinking a lot of caffeine. I addicted caffeine more than eating a regular meal. So, in August 15th I experienced of feeling heart racing and shortness of breath, then the feeling has stopped in around August 28th after I took medicine for anxiety. However, for 10 days I have begun to feel left mild chest pain and left bicep pain. I visited a doctor in last weekend, he says you are fine there is no problem, it could be from stress or ribs. But, I always afraid that my heart gonna stop. I dream about my heart sometimes. I also, cry, and I afraid to stay alone , to drive a car for traveling, to hang out with friends that smoking weed or cigarette or hookah, because, when I smell or inhale one of those, I think that I will have heart disease. Otherwise, to be more specific, currently, I begun eating normal, going to the gym, trying to drink plenty of water, I am not drinking soda and never alcohol, because I am so concerned about my health. Last night before I sleep, I felt chest pressure on the center of the chest, and the feeling stopped in few seconds. I am still afraid, please help.