I say he’s going for treatment of a medical condition he doesn’t want anyone to know about. You know, the one he’s been hiding by not releasing his medical records. What better cover than to visit his grandma in the “hospital”. And why just two days? Does he somehow know his grandma will be okay in 48 hours. Or does he need that long for the procedure and recuperation?
He is awfully skinny
Sort of like The Bent One faking the fall off the stairs at Greg Norman's house to create a medical time window to have Willard straightened, so he would be in the clear in case he ever were required to drop trou to have the court verify the distinguishing characteristics Monica and Paula described?