What Causes Agitation, Memory Loss, Sweating And Erratic Behavior While Treating Heart Disease?

Dear Doc, My father-in-law is diabetic, had an open-heart surgery n several stints placed in his veins. he suffers from chronic pain and has taken methadone and valium for years. Yesterday he went to the restroom, started to get erratic, got confused, got of the bathroom naked yelling, sweating n went looking for a medication that help him poop. Did not remember the medication name and started to look for it in unlikely places, took other medications, dumped them in the wash basin and turned on the tap. The bathroom was a mess, poop everywhere. Once out and downstairs, he fell could not get up. An hour later we helped him on his feet. At the hospital doctors found his kidneys are affected. Today his kidneys have recuperated well and he is much better. Tomorrow they re gonna use a camera to scan his heart and veins. Question: What caused his agitation, sudden loss of memory, sweating and his acting erratic? Doctors suspected he had a silent heart attack earlier. Please answer my questions. Thank you doctor.