Pale yellow/grayish poop

Has any one had a toddler have pale yellow-grayish stool? My 2 yr old has had it since Feb 3rd. His stool sample (the only tested for bacteria 🙃) was negative for bacteria but the color is concerning and the fact that it's been going on for a couple weeks now. If you experienced this, what was the reason? Google suggests liver function problems or possible celiac disease.