I'm very sorry for your recent loss. Did you check whether there were any changes in the food with the manufacturer? It's not always on the bag or on the website, you'd have to phone or email them. I did find this recall, but would you be feeding two large dogs this food?
https://www.hillspet.com/our-company/...-dog-food.html
I've never fed Science Diet to my dog. I'm not sure what Blue Diamond food is. I know of Blue Buffalo, which I don't feed but many here have had loose stool issues with. I fed a Diamond food myself with no problems, other than it was very low in calories and I had to feed more of it. Even though it was not one of the Diamond foods that had recalls I stopped feeding it after the second big recall that company had a couple of years ago.