When i concentrate on breathing and take deep breaths i seem to have difficulty breathing after 1st or 2nd deep breath as if there is some sort of block that lasts until i stop breathing deeply... went to doc&had ekg/xray/bloodtest doc saidnottoworry?

Doctor can evaluate: A person who "can't take a deep breath" (which may mean different things to different people) can write down his daily symptoms on a big calendar, and get rechecked by his primary care doctor. A pulmonologist, or a cardiologist can help if needed. Importantly, if there exists a problem, symptoms should exist regardless of whether or not the patient is "concentrating" on breathing.