What's wrong, Fat Rat?

I'm worried about Fat Rat.
Something is wrong.
Two days ago, I saw him sitting in his food bowl, which was the first time he ever did that.
It reminded me when 鸡蛋糕 died. She had passed on peacefully in her food bowl then.
I came to the conclusion that it was where they felt the safest.
When I asked him what was he doing in there, he suddenly went into a panic attack and shot around the cage.
Something is seriously scaring him more than usual (he has always been a coward), and I don't know what.
Even today, he was still in a panic attack.
When he finally stopped, he froze.
I tried using food to calm him down, but he just stood a distance.
What's happening to him?
Sobs.....