Next advice I would give is to go back to the shot. Stand and take a deep breath and very calmly take a look. Folks get all hyped up and will run by a critter several times and not see it. Eventhough an elk is big, they can pile up into a hole behind a log fairly easy. I know you are feeling the pressure and starting to feel sick over it. Just be calm. Angle of the shot would be helpful. One lung, two lungs, angled for lung and liver.....How did the bull react? A fat chunk can roll into the hole and plug the blood. They can bleed out inside without spilling much blood.