In one sentence, describe what the following article is about:

Diarrhea in infants is often caused by an allergy to ingredients in their formula or baby food. To avoid this, consult your doctor and have your infant tested for allergies. If allergy tests confirm your child is allergic to something, don't allow them to consume it in the future.  Many infants are allergic to milk protein, which can cause diarrhea. Some babies can outgrow food allergies, so talk to your doctor as your baby grows. An allergist may also be able to help you decide. Whether it is before or after you’ve tested your infant for allergies, you should consider switching their formula if your baby gets diarrhea often. Talk to your pediatrician before changing formulas. After switching, you may find that your infant no longer has diarrhea. If you use a traditional dairy formula, try using a soy-based formula. While rare in children, lactose intolerance can cause  cramps, gas, or diarrhea. Your pediatrician can test for it by giving your baby a simple breath test. If the test confirms lactose intolerance, you'll need to put them on a lactose free diet.

Summary:
Have your child tested for allergies. Switch formulas, if you use formula. Test your infant for lactose intolerance.