Can’t put weight on my 2 year old

[lettuce]

We thought he had EPI, but two of the Texas tests came back negative. He dropped all the way to 45 lbs! But he’s gained some weight but eats a ton 8-9 cups a day. Super rambunctious and jumping all over the place. Eats fine, poops fine, energy overwhelming. The only thing left is a colonoscopy $3000 to see if he has ibd but he’s never puked, and with switching him to royal canine German shepherds his poops have came back