Feeder size question

[Jessika]

We have a king snake, not sure how old he is but we've had him for two months and he's about 18 inches long. He was eating 2 pinkies every 4-5 days, but was always looking for more. After speaking with the reptile specialist at the pet store, I decided to try him on a small fuzzy. He got it down quickly, but the skull of the pinky was protruding from him, a horrible huge lump. It went away after a few hours, all that remains is a lump a bit bigger than him in the middle of his belly. I'm concerned that the protrusion may have caused some damage... am I being paranoid? Should I move him back down to pinkies again? Thanks so much for reading