Hi Welcome to the HCM An episode of acute gastroenteritis can deplete a child of vital electrolytes sometimes if not rehydrated properly during the episodes. This is known as electrolyte imbalance. It seems your child might be having either an electrolyte imbalance or a rare probability may be benign acute childhood myositis episode(BACM). I would suggest you to go for a proper clinical examination followed by laboratory evaluation of serum Sodium, Potassium and calcium levels. In case BACM suspected, CPK levels will be helpful. In the meantime you can give her Acetaminophen for pain relief along with oral rehydration therapy. For further questions, do contact us.