I would wait until he is a couple of inches across before offering something as large as a nightcrawler. Just give it time, pacmans don't need to eat a ton of food anyway, and it may just be stressed out from being offered food a little too frequently on top of the infection treatment. Time, patience, and alone time should fix it up.
The story you describe with the toad in highschool sounds more like it died in the cage, and the beetles ate it, starting with the softest part of the body first. Once in an animal's stomach, the acid inside kills it, or at the very least they are not in there long enough to pupate and turn into beetles - that's a process that can take a week or more! I hear this frequently, and every single time it has been because the animal died prior, and the beetles/superworms/mealworms/crickets ate the animal after it died. This story is like coming across a cow that's died in a field, and a vulture is eating the cow, so you assume the vulture killed the cow. All feeder insects are opportunists, and will feed readily on a deceased animal. They do not eat their way out of the stomach.
-Jen