Milk or Soy Allergy Possibly?? Need Feedback!

Curious on how you know if your infant has a milk or soy allergy. My daughter will be 2 months in 3 days and recently over the past few weeks she has been having slimy, watery /green/ yellow poop. She is formula fed & I currently have her on Enfamil Gentlease. She is not fussy after feedings, does not vomit, and has 1-2 bowel movements a day now that she’s got older. But the consistency is what is making me wonder if she has an allergy. Pics are examples of recent poops.