It could be your temps that are causing him too much stress for him to eat. If his water temperature is 87 degrees and his basking spot is 92, there is only a 5 degree variance there. He isn't able to properly thermoregulate. You might try to back that water temperature down to approximately 78 degrees, then boost his basking temperature to about 100-105, but allow for enough land space that he can move away from the lamp. If you allow for this then it will have a direct basking temp of about 105, but then if he moves just a little over it will drop to about 95, then 90 and so on and so forth. You will be allowing him to choose his preferred temperature. With your current temps, he doesn't really have that luxury.
Chris
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