K.F.
Have you tried taking dairy out of her diet for a few weeks? Dairy causes a lot of problems for little ones (and big people too). My son has been dairy intollerant for most of his life and may still be. When he was younger, he had really bad gas and cramping. We are now doing a dairy trial and he is getting constipated (I've only given him less than 1/2 teaspoon of powdered milk per day!) . All this to say, dairy can be really problematic. It is worth a try.
You probably know this but you should also avoid rice, bananas, and processed white breads while she is constipated because those will only stop her up more.
Good luck.