Probably taking the biggest crap of life in his pants!
First of all, the Doctor was a cardeologist, he should have NEVER been able to process those drugs. Second, there was an acute amount of propofol and the doctor admitted to this. Right there he is in trouble. There are only two possible stories here. The doctor is a bad doctor who really didn't know what he was doing. He was just giving and giving Michael the drugs until he fell "asleep". When Michael died the doctor probably went into shock and probably didn't know what to do. Hence the reason why he took so long to call 911 and the reason why he probably was to freaked out to perform cpr correctly.
Second story is that the doctor was sent there to kill Michael. Or, now seeing the doctor's reaction, someone had him threatened to kill michael. I don't see how someone, doctor or not can continue to just give and give a man drugs every hour like that. I'm not a doctor and i know that's a problem. Also, what if Michael was already asleep or drowsy and the doctor just continued to put in the drugs? All i know is that if it was murder and intentional then murray is probably going to sing like a canary and reveal the missing links and missing people.
Also, i blame the two molestation trials and the press for this too. If the press wouldn't have been so hard on him, and if the trials wouldn't have happened then Michael most likely wouldn't have had insomia and problems with sleeping.