A doctor can tell if your child has hand-foot-and-mouth disease by the symptoms you describe and by looking at the sores and blisters.
Roast the beets for 50 to 60 minutes. Cook the beets until tender, checking them by inserting a fork into the center of each beet. When the fork glides in easily, the beets are tender enough to remove from the oven.
Preheat oven to 375 degrees F. Coat beets lightly with oil. Wrap beets in aluminum foil, place on a baking sheet, and roast in the oven until cooked through, approximately 45 to 60 minutes. Remove from the oven, let cool for 10 minutes, and then peel and slice into 1/4-inch thick slices.