Shot elephants can be deceptive. An elephant shot through the heart may just turn and run, without showing much evidence of having been shot. Until it drops dead a few hundred yards away.
Agree with most (all?) that the second shot was almost certainly from the PH while less sure about the third.
My Ph’s guidance was that once you shoot at an elephant, keep shooting, regardless of the effect (or lack thereof) of the first shot. He also said I could try for a brain shot if I wanted, but if it was a miss, he recommended he take a back-up shot while I reloaded. Of course, his advice may have been impacted by the fact that we were about 300 yards from the Botswana border . . .