that is such a tragic story. When dogs are in pain they will look for their caregiver to relieve that pain. There was a story of a guy that we know and he is a bit traumetized by it: His dog was acting strange and doing things it wouldn't normally do like always sitting really close to him and panting a lot and following him everywhere and because he was trying to go to sleep (the human) he put the dog outside so that he could sleep in peace. The next day he woke up and the dog was lying next to the door with her eyes glazed over and panting really hard. He rushed to the hospital but the dog died in the car on the way there. If your dog is all of a sudden acting very different to how it normally does and is following you there is a good chance that the dog knows something is wrong with it and needs you to help.

I'm very sorry that this happened to you.