Hand foot mouth disease is a self limiting viral disease. There is no specific treatment for that virus. Rashes are generally painless without itching. Mouth ulcers can cause pain while swallowing but they resolve early. Body rashes can last for 7-10 days. Give medicine for fever(if there), Dologel mouth paint will help in case of mouth ulcers. Increase her fluid intake( Soup , Fruit Juices, Water).
Next Steps
Rashes appear after fever and sore-throat and generally progress over 3-5 days and then start healing with scab over few days. Visit local pediatrician in case ur child is irritable, drowsy or complaining of uneasiness.... that can be a sign of complication ( seen rarely)