I don't think the mealworms did anything to him, especially since he's behind your dresser. Maybe he dropped his tail while escaping? How did he get out of the cage? Is there a screen cover?
I'd say to let him be until he's calmed down from the escape. I've read of people putting different things on the tail, but since I haven't tried it, I don't know if I should recommend something I haven't tried
Maybe someone who's had experience can reply to that part.
I'm just curious as to how he got out this 2nd time out of his cage? With my 1st leo, I kept a dish of mealworms in all night and took them out to gutload in the day with no problems... even the mealworms that escaped the dish didn't hurt her.