Again, this is from experience with Collared Lizards, but I suspect might be similar... when they want to brumate, they may stop eating, but they also are sleepy. Instead of seeking the basking spot, they find the cool places in the enclosure and sleep there. Sleeping more hours, and failing to eat because of being too sleepy were the signs that my collaris were going to brunate... not just the cessation of eating by itself.
So I go with everyone else in saying see a vet.
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0.0.1 Bearded Dragon
1.0 African House Snake
0.1 Albino Corn Snake
1.0 Red Sided Garter Snake
0.1 Peromyscus leucopus (White-footed mouse)
2.5 Turkish Angora (show) cats
Antioch Turkish Angoras
PuRRS Rescue