7m old low grade fever of 101.5 (day)103 (night).Two red spots on his cheek and sore on the roof of his mouth has a bit of diaper rash? Cause?

Hand foot, mouth dis. Hand foot and mouth disease is most likely. Causing sores on the palate, around the mouth, in the diaper area, and hands and feet, they look like red spots or canker sores (white discs with red around them). Fever and pain are possible. It's viral and runs its course. Pain control is key. If this doesn't sound like what your child has, get it checked.