my dog passed away very suddenly yetserday it had been off its food all wekkend and wouldnt comeee out of the kennel on the saturday it was bein sik and on sunday night it had blood in its stools and was frothing at the mouth i was going to take it to the vets onmonday morning but it passed away. The dog was six month old springer spaniel and was up to date with all his jabs i dont understand what has caused his death