Like Mimi said, check your daughter's environment as well as the food she is eating. Detox your home. That means shampoos, conditioners, bath soap, laundry detergents and household cleaners. There could be something in the laundry detergent you are using that is causing a skin reaction. Bath soap, toothpaste, cleaners used for cleaning your house, carpet, floors, etc. It's amazing the things that can trigger skin irritations both from the inside and outside environment.
I use Shaklee's Get Clean cleaning products in my home and nothing else. They are safe for children, the environment, are much less expensive than other green cleaners on the market and they actually work. You may have seen them on Oprah or Rachael Ray. If you want more information on them, please contact me.
My daughter had visited a friend when she was younger for a sleepover. They slept on the sleeping bags on the carpet in her friend's room. When she woke up the next morning, any part of her skin that had touched the carpet was covered with red bumps very similar to what you are describing.
In talking with the mom, she had used a carpet freshener on the carpet.
It also helps to keep a log of activities and food she eats throughout the day so you can see what may be triggering the reaction. That helped when I was a child breaking out in "giant" hives. We found that peanuts, tomato sauce and definitely stress were all contributing factors. I've outgrown the allergies and manage the stress.
Your daughter will be fine. Take care. God Bless.