Feeling guilt, please respond

I work in a sub-acute rehab. Last week we had a patient who is admitted with pancreatitis. I received him four hours after his admission from the hospital. Immediately upon meeting him, he wanted to leave against medical advice. When it was explained that he would not receive services at home if he left AMA, he decided to stay

He then complained of pain to the lower left back where he had a surgical incision, and I gave him Tylenol for the pain. He was prescribed Percocet but this was only 5 hours after admission and we did not yet have the script from our doctor approving of the narcotic. He then started complaining of other abnormalities. he complained of generalized pain for which I called the doctor. the doctor called in his script for Percocet, and that was it. however, at this point all of his vital signs were within normal limits except for a slightly elevated pulse. For the post I had him perform a valsalva maneuver. This seemed to help with some relief. He then started complaining of just not feeling right. again I took his vital signs everything was normal, I auscultated his heart over the aorta with S1 s2 no murmurs. Just tachy. Apical pulse 100. Lung sounds clear, no SOB breathing easy and unlabored. No JVD, cap refill brisk, normoactive bowel sounds. Skin turgor good, skin clear and pink. and I called the director of nursing to come assess him. she did and said that everything was normal. I called the doctor about his complaints and she did not have any new orders. He then complained of shortness of breath I called the nursing supervisor who called the doctor and got an order for duoneb nebulizer treatment and to send him to the hospital if the shortness of breath continued. We apply the nebulizer and within 60 Seconds he started exporating white sputum and went unconscious. He had no vital signs. CPR was initiated. 911 was called, a code was called. They weren't able to bring him back.

I know this post is very scattered but my brain is very scattered right now. I feel like I killed this man. That my lack or knowledge or experience prevented him from the proper care.