I quit smoking 2 weeks ago I used to smoke less than a pack a day for about 3 years, right before I quit I began to feel a slight chest pain that occurs 4 or 5 times a day mostly in the left side of my chest and then it disappears in a minute or two and that's it, no cough no tightness nothing but it worried me a lot so I quit now after 2 weeks I still experience the same pain, what could it possibly be?