<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been feeling a little dizzy lately and my heart rate keeps changing. Also, sometimes I feel short of breath.  <response>: It sounds like you might have heart block. Heart block is a condition in which the electrical signals that regulate the heartbeat are disrupted, causing a slow or irregular heartbeat, decreased heart rate, increased heart rate, and other symptoms. You should get some tests done to confirm the diagnosis. 