Health extention food

My shelties were eating merick bg salmon up until they stoppped making it. No other food seems to work for them. Ive tried other foods from Merrick they got diah even after a slowgradual switch. Their breeder feeds diamond bc its what works for her dogs but with the recalls I wont feed any diamond products. Right now they are on Fromms adult gold my lab is doing wonderful but my shelties are pooping tons and my older one is now eating tons of poop outside and pooping in the house something he has never done. My breeders friend who breeds and shows cavalies has been feeding Health extention adult original and she lives it. Anyone tried it or have any feed back on it. Guess it wouldnt hurt to try. My other option is Canidae. Looking for something pricewise comparatable tfromms I pay 50 for 30lbs.