Hello I Am A New Grad Rn Just Started A

Hello I am a new grad Rn just started a new job less than a month ago and it is so busy it's crazy! Anyway I couldn't find the old fentynal patch on my patient it was25 mcg and I applied the new 50 mcg patch in the mean time the patient also received new order for decadron and to increase her oxy from every 8 hrs to every three this is a terminal patient , the DOn called me stating it was my fault for not removing the two day old 25 mcg patch, my question is there were many changes in the last 12 hours with meds couldn't it of been any of the changes . Also the second patch was on for less than 15 hrs?