hi my 10 week puppy has just started to have sloppy stools i think i know what

the reason is- she was on pedigree didnt like it so weaned her onto james wellbeloved dry food, she was fine with that. i wanted to add abit off wet food in with it but i think i mite have given her too much straight away as it only been four days since i put her on it? do u think thats what it is i weaned her on it too quickly and feeding too much? they not sloppy sloppy but they re not hard and they are a lighter colour and look like a snail-sorry??? she has been wormed every 2 weeks since she was born.