My younger daughter wasn't vomiting, but was very frequently complaining of abdominal pain. She had allergies and the doctors said the tummy problem was postnasal drip. She was put on antihistamines and allergy shots. It helped somewhat. She was frequently sick. She was frequently on antibiotics. We knew little about probiotics at the time (she is now 21).
She eventually developed asthma, hives, and other immune-related problems. She had to be on TWO 24-hour antihistamines per day, plus one 24-hour antileukotriene, supplements seasonally, nose spray, etc.
Now we know more about Candida, probiotics, and food sensitivities. She is on a gluten-free, dairy (cow casein), egg, and soy free, mostly organic, mostly whole foods diet.
It has made a world of difference in her health.
I am so grateful for the Internet.