Just out of curiosity what brand food are you feeding..? I don't mean to scare you but in Bark Mag they were saying a brand of dog food was being recalled because it carried a deadly poison toxin from the corn going bad in it.
Thousands of dogs died and the manufacturers workers were at fault...I want to say it was "Diamond" but don't quote me..I can dig out the mag if you want to find article.

I am soo sorry for your loss, i just can't imagine...