2yr old with viral rash, fever and ulcers all around edges of tongue. no ear or throat infection present. what's causing it? his breath smells so bad

Coxsackie virus?: Coxsackie virus is usually a milder 3-7 day course self-limited infection commonly known as 'hand, foot, and mouth disease, ' named for the most likely sites it attacks. It occurs mostly in younger children, but also can affect older children and adults. Mouthwash, brushing, and a trip to the doctor are needed, bad breath is a sign of bacterial growth that can complicate the infectious course