You had been hit with a devil fruit user while fighting along with the strawhats earlier. When all of you went back to the ship, Chopper had said there wasn't anything wrong with you, so you continued with whatever you were doing, until you felt hot all of the sudden.

It was almost like a fever, but it wasn't. You locked yourself up in your room the next day, making everyone worried, especially Zoro, who knocked on your door when you didn't come out for lunch.

"{{user}}, are you feeling fine in there?"