Where did you get the lizard?

Everything sounds ok ( not serious ). Once you change a dietary item it may take a couple of days before you actually see a change in the scat. You're not overfeeding. He may be staying down burrowed because of improper temps, or he may be preparing for hibernation. You have proper lighting, including UVB?
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"A man that should call everything by it's right name, would hardly pass the streets without being knocked down as a common enemy." The Complete Works of George Savile, First Marquess of Halifax 1912,246