See below. Lorazepam is not a medicine for coughing or shortness of breath. You may have asthma, emphysema or a number of other lung diseases. Get yourself checked by a pulmonary specialist. And if you smoke, stop - that will improve your symptoms.
Usually no. Emphysema is a specific lung disease caused by smoking. If you are not a smoker, it is unlikely to be emphysema. A simple cxr and a visit to your doctor will clear that concern for you. I would be more concerned of other illnesses that are treatable. But you need to see a doctor for this. The causes of cough, dyspnea on a young person need to be worked up.
Maybe. The reasons for coughing and shortness of breath are many and to tell what the reason is in you requires examination and testing. You need a doctor to ask you questions, examine you, order appropriate tests, and then put all that together. Do you smoke? Do you have a fever? Are you more short of breath when you lie down? Answers to such questions can be very helpful.
Yes. Emphysema can present with all of these symptoms. To start to make the diagnosis one needs a chest xray and pulmonary function tests.
Possibly... If the person has smoked, then empysema is a possible etiology of these symptoms. Other possibilities include gerd and post-nasal drip, bronchospasm or some combination of these diagnoses. An evaluation by a doctor as well as testing will be necessary to make the diagnosis and render treatment. If currently smoking, need to quit asap!