Is the mass hard or very soft? If it's new and soft, it could be gas trapped in there by some sort of blockage. Did the blockage exist before he pooed on you? was there any swelling before the regurges(perhaps you assumed they were from the prey items?)? Were these the first feedings ever? At 74g, he's very young or he's been losing weight.

Your temps seem like they might be slightly off(too high AND too low). Does he have plenty of hides on both cool and warm sides?

A prey item from 6 days before shouldn't have been recognizable as a prey item, imo. If he regurged something that looked whole from 6 days before, there is a major issue.

At any rate, it might be time for a vet visit.