Hi Breathing difficult is categorised into different grades based on severity whether the difficult in breathing is at rest or exertion. Apart from respiratory cause there are cardiac and metabolic causes also which may cause difficullt breathing. High homocysteine levels are found in number of metabolic disorders. Please see a General Medicine doctor for further evaluation and management. In case of further doubts, please feel free to write back to me. Regards Dr Prashik Meshram