Hi Read your query I am Dr Saumya Mittal And I will try to explain you the possibilities First and foremost, dont give him water by mouth while he is unconcious, he may aspirate. In fact the sudden onset of loss of conciousness with breathing disorder may point to lung and/or heart problem Second, the loss of conciousness usually means a brain problem. There may be a stroke, which may bot show up in a ct scan for 6-24 hours. or there may be an infection like meningoencephalitis. An MRI would be a better test. Third, there may be some metabolic derangement. I would suggest checking his electrolytes and ABG (arterial blood gas). There may be a possibility that he has indeed aspirated, which may show a little late on the chest x ray. The abnormal aspiration causes reduced oxygen supply to the brain, causing loss of conciousness. An MRI would be advisable. A possibility of heart conditions may arise and so and ech and echo are advisable. I hope this helps you. Inform the reports mentioned above so i can be of help further. Best of luck. I have given you the answer to the maximum considering the information provided. The results of the tests could further enhance my answer to you. Please do understand that some details could be extracted from a detailed history and examination. Looking forward to your return query with the details asked so that I can help you further. (If the answer has helped you, please indicate this)