The chat function was not working for some reason so I hope you don't mind this way. I am concerned for your boy as a hiding cat usually means that they are in pain or otherwise not feeling well. My first reaction would be to have him checked at the vet for something common such as a urinary infection.
Are there any other changes, such as a lack of appetite, frequent trips to the litterbox? Is he drinking as normal? Any small changes could indicate something and give us something to go on other than the hiding.
The only other thing is if there was some sort of scary or traumatic (for him) event that occurred at the times he is hiding. Maybe a new to him dishwasher or washing machine running? anything at all that he may not like the sound of?
I hope these ideas help. Assuming that there have been no changes to the home or scary events, I would start with a vet appointment. If he stops eating that indicates an emergency as this can damage the liver in as little as 2 days.....
Please keep me posted and let me know if you think of anything at all that may help give us something to go on.
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