I am not feeling well when i am on treadmill, kindly suggest

I joined a gym today and after ten minutes of jogging on the treadmill, I was physically sick. I was nauseas and I began to cold sweat... it literally took me five minutes for my heart rate to return to normal...then I was faint and dizzy. My trainer thinks it is due to my lack of training, which I am not sure about as I do salsa and tons of pilates. I however have a cardiac arrythmia and am asthmatic... my doctor thinks that it is not life threatening...but if my heart or respirtory problems are the cause of my issue with cardio... how can I control it? well i was pulled out of physical education class in 8th grade.