I am 20 weight 92nd 5 ft 9. i recently started having shortness of breath after 1 hour of exercising. i got all the test and were normal?

Deconditioning: Most likely, if you have not been exercising for a while, you have become deconditioned. It will take some time for your body to adjust to exercise. Unless you are coughing or have other symptoms of exercise-induced asthma, I would encourage you to keep up the efforts. Start for 15 minutes per session, & gradually increase the number of sessions & duration to 30 min to get best results. Keep at it