I had these same symptoms with my 5 year old daughter she woule be fine most the time then would lay down and complain about her tummy hurting she ended up with a fever of 105.4 i took her straight to the ER and she had a sever bladder infection. if your daughter takes lots of baths or mostly bubble bath and if she is potty trained and she is wetting the bed at nice. that is a tell tell sing hope this helps.
This year there have been many virus/bugs going around especially stomach related , if she still has a fever and seems worse take her to see the Doctor to be sure ,its nothing more serious I also would say keep her hydrated ,with plenty of drinks .