Trouble breathing is known as dyspnea. It is also known as shortness of breath or SOB. You may feel like you do not get enough air when you breathe. This is caused by different things. It comes normally after you exercise, run, or do tiring activities. When SOB happens often and suddenly, it may be a sign of other health problems. Treatment depends on the specific cause of trouble breathing. Your doctor will ask for more tests to find the cause and give treatment.