I Am Coughing, Discharging A Lot Of Sputum. I Experienced

I am coughing, discharging a lot of sputum. I experienced an attack where I felt short of breath and was gasping for air, the attack lasted for some 30 to 45 minutes. I had similar attacks only recently but not so severe.

I go to the gym 4 days in a week, I am on the treadmill for 30 minutes on each of those days and covers 4 km in the 30 minutes. I first experienced gasping for air whilst exercising on the treadmill.

Should I be worried with this or it will pass after the cough.