i will put down my experience below, hope to find help from you as I'm in very bad condition now.
I was smoking for the last 14 years, 20 cigs a day. but i usually go to gym and sometimes i stop due to work or family commitments pressures. I went back to Gym like 4 months ago, after three months I started to feel some numbness in my arms, i called my cousin who is a GP doctor to ask where to check with neurologist or Cardiologist and he said check neurologist first but if you dont feel tightness in your chest then dont worry may you pressed yourself in the gym or were sleeping on your arms. any way after a while I was out with a friend and had late heavy dinner and went back to sleep, I woke up 30 minute later with left arm numb and tight chest, i went immediately to ER and they did ECG they said everything is fine, the next day i quit cold turkey. after that I did many check ups with cardiologist like ECG, treadmill ECG, Echo and all came good, i started to have signs like headaches, nausea, no appetite for food, cramps and strange feelings with tight chest, heartburn and difficulty breathing with other things .... doctor told me it is nicotine withdrawal symptoms and frankly i'm not coping with them very well, my work is stressful and i took 2 weeks vacation from work and went back but nothing improved, i cannot take vacation for ever you know, its been 21 days, any previous experience will help guys ... I'm very desperate, most likely as i think is that i'm having anxiety attacks according to the search i did .... i prefer somebody who has been through this to tell me how long this situation will last ... your help is highly appreciated