Jenny is a 4 year old girl who is seen with her mother who has noticed small ulcers in her mouth this morning. Jenny has complained her mouth was hurting, but despite this she has been maintaining her usual oral intake. She has no other medical history and is up to date with immunisations. She complained of a sore throat a few days ago but this has since settled, and she is attending pre-school as normal.
On examination there are small yellow-grey ulcers in her mouth with an erythematous halo, and her tonsils look normal. A 3mm erythematous macule is noted on her right index finger. Her observations are all normal and there is no rash elsewhere.
What is her most likely diagnosis?