It sounds like you have noticed a sudden change in your exercise tolerance. Any time this happens, it is a good idea to see a qualified physician. Since we cannot be sure what is causing this problem (heart, lungs, or other), then you will need to see a general internist
What you are describing is what we call dyspnea on exertion which is the technical term for too much shortness of breath with exercise. When someone comes to a doctor
with this problem, the first organ we need to look at is the heart. If your heart is not pumping as well as it is suppose to, then you will become more short of breath with lesser and lesser exercises. The best test for your heart depends on the details of your symptoms. Your doctor will likely want to order a couple blood tests, possibly an echocardiogram
, and/or an exercise stress test. In addition, your doctor will want to look at your lung function. This may or may not include pulmonary function tests to look at how well you lungs are getting oxygen to your blood.
I suggest you schedule an appointment to see a doctor today (or ASAP). He or she will be able to take a much more detailed history of your symptoms and perform a thorough cardio-pulmonary exam. Hopefully, you will get to the bottom of this soon.