It sounds like your daughter has pin worms. Pin worms and GERD are two separate problems; it just so happens your daughter has GERD and may have pin worms, too. Here's some info regarding pin worms.
Pinworms are small, white worms that live in the intestines. Pinworm infections are common in young children and are easily treated.
If your child is infected with pinworms, you may notice him or her moving around a lot in bed at night or being unable to sleep because of an itchy bottom. The itching is caused by the female pinworm that comes out of the rectum to lay eggs around the anus (the opening to the rectum). Sometimes tiny white worms (shorter than 1/2 inch) may be seen on the child's bottom at night or they may show up in the child's bowel movement.
Pinworms are easy to get. Pinworms are usually spread from child to child, and the eggs can be picked up on children's fingers when they are playing. Eggs can stay or your child's skin for several hours. They can survive for 2 weeks on clothes, bedding and toys. If the eggs are on your child's hands or toys, and your child puts their fingers or toys in their mouth, the tiny eggs can enter their bodies. The eggs stay in the upper part of the intestine until they hatch. After they hatch, the worms move down the length of the intestine, and then out the anus where they lay eggs.
When children scratch their itchy bottoms, the tiny eggs can get under their fingernails. As the children move around the house, the eggs may be spread, and other family members may become infected. Sometimes adults breathe in the eggs when the bed covers are shaken. However, this is very uncommon. Children easily infect each other while they are playing and by not thoroughly washing their hands before eating. Pets do not spread pinworms, although they may carry their own kinds of worms.