You may want to try a multi vitamin supplement on his next feeding. Sera company has a good one called reptimineral. There are others too such as reptivite. I would only supplement his food maybe once a month (if that), but what it sounds like is a bit of a nutritional disorder. Nothing to worrya about, but that is the only other thing that i can think of. If he has been fed F/T mice all of his life, it could be just a minor thiamine deficincy. Nothing to panic about. Goodluck.
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1.0 ball python- Azazel
1.0 columbian boa- Brooklyn
1.0 JCP-Milton
1.0 borneo blood-Hiss
1.0 peach phase thayeri-Sancho
0.1 creamsicle corn- Pandora
1.1 hognose- Pricilla and Odd
0.1 russian tortoise- Manja
0.1 leo- Boji
0.1 beardie- Indie
1.0 BTS- Griffon
0.1 Iggy- Sunny
0.1 pacific parrolet- Mishka
1.1 cats- Cairo and Oberon
2.4 ratties- Willard, Rizzo, Bree, Blitzkreig, Raisin, and the Runt