Hello, My Daughter Is 3 Years Old. She Has Been

Hello, my daughter is 3 years old. she has been experiencing bloating, abdominal discomfort, foul gas and occasional vomiting empties stomach and is relieved from pain, this has been occurring on and off for a couple weeks. She has had a history of gastroenteritis, hives, rash around the mouth, worsened eczema, lactose intolerance. I am concerned she may have another food intolerance I am unaware of. what is your thoughts and how can I manage these symptoms?