What should i do if i have asthma.after doing any kind of prolonged exercise, i can't breath properly for a day or two?

See a physician: An asthma attack can occur during or immediately after prolonged exercise, or even 4-6 hours following due to a delayed reaction. Using your albuterol inhaler prior to exercise can minimize these attacks. However, your breathing may also be affected reasons other than asthma, and so seeing your doctor for a full evaluation would be a good idea.