Stomachache?

As Zeke's eyelids fluttered open, he was immediately met with a pair of silvery moonlit eyes who were only less than an inch away from him.

Zeke: !!

His fur immediately stood on its end and he shot up to his feet with a fierce hiss. All traces of sleepiness dissipated in an instant and the entire cat entered a state of great alert. 

What are you doing?! Do you want to scare me to death?! 

It took one full second for him to realize that he was back in a familiar cabin and the person in front of him was none other than the stupid assassin. The last time Zeke had seen him, he had been laying on the ground, groggy with fever. But now… Zeke could not find any sign of sickness on his face, save from his slightly paler complexion. From the time when he awoke in his original body up to when he lay inside the medical cabin in the institute, only a few hours had passed. Was it possible for someone who had a very high fever to recover this fast?