Hand, foot and mouth disease. Hand, foot and mouth disease is a common, contagious infection that causes mouth ulcers and spots and blisters on the palms of the hands and soles of the feet. It’s most common in young children (particularly those under 10), but it can also affect older children and adults.
https://www.nhsinform.scot/illnesses-and-conditions/injuries/skin-injuries/skin-rashes-in-children