I am having this problem for more then three months.When I have problems with my breathing I feel like the problems comes from my upper stomach.Running is my hobby,and when I run I really don't feel any problem with breathing.But suddenly I first feel some weird feeling in my stomach and after a while breathing problem apperars.
I am 31 years old and I quit smoking 2 years ago
Please help me

Strenuous excersing can sometimes cause a weird feeling in the stomach or nausea but if it is accompanied by breathing problems then I would recommend you see a doctor as soon as possible.