What Causes Breathing Problem At An Old Age?

My brother is 67 and is a sever diabetic. He has been trouble breathing lately. He finally went to the doctor yesterday and they did blood work, said they would get back to them. They suspected it was either a blood clot in his lungs or heart problems. They called back this morning and said it is not a blood clot. They called him in a prescription for Nitro Glycerin and told him to take an asperin, and they would get back to them with an appointment with a cardiologist. They finally calle back and said they could not get him in until the 23rd. To me, this is rediculous, to give someone Nitro because they are having heart problems and expect them to wait for a week to get them to a specialist. I am thinking congestive heart failure, guessing, but our mother had it and her father had it. Does that run in the family and am I over reacting?