I raised my painted from a hatchling, he's 12 years old today.
He went through what I called growth spurts. He wouldn't eat a lot then all of a sudden out of nowhere he was eating everything in sight. He'd do that for a little while then go back to not eating a whole lot.
Each time this happened he did grow. He did that off & on for years until he reached his adult size then tapered off.
Today he eats well but he doesn't have bouts of that ravenous appetite. Maybe your little guy is going through a growth spurt right now.
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PHRatz