Original sentence: At the end of the episode, Bart says he ate a lot of shrimp in the green room, but five seasons later on the season 18 episode, "Please Homer, Don't Hammer 'Em", it's revealed that Bart has a shrimp allergy
Edited sentence: At the end of the episode, Bart says he ate a lot of shrimp in the green room, but five seasons later on the season 18 episode, "Please Homer, Don't Hammer 'Em", it's revealed that Bart has a shrimp allergy, though it is possible that Bart gained this allergy sometime inbetween the seasons