Hello dear, thanks for your question on HCM. Since you are smoker, in my opinion you should first quit smoking. Because this is the culprit for your symptoms of back pain and breathing difficulty. X ray finding of increased bronchovascular markings is suggestive of early lung damage due to smoking. So better to quit smoking as soon as possible. Enroll yourself in pulmonary rehabilitation center where chest physiotherapy and deep breathing exercise are done. These will help you in taking deep breath.