[GuinnessStout]

Just went thought testing with Guinness after they found crystals but during that same period I was switching flavors of his food because I switch up each time I get a bag to mix things up well by the time we went back for more test he was back to normal so my vet said odds are it was the last flavor had too much of something that caused it and just to avoid that flavor... We have even had him retested again just to be safe and still normal.