Oh how sad! I am so sorry your dog died. You obviously were doing your best for him, and took him in for the bloodwork, etc.
A sudden death like this is always hard to cope with. It leaves too many unanswered questions, and a lot of "what-if's"
There is no way you could tell for certain what was the cause of his death, without having a Necropsy performed. Of course that won't bring him back. It might be better to let him rest in peace.
You have my sympathy. I am so sorry.
If you get any more dogs, you might want to make sure they are not eating
any poisonous plants around the house that may cause this also.
Or could it have been Parvo?
Parvo has symptoms as you described also.
Sorry for your loss. I have 4 rescues now, but have felt the sadness of a lost one.
I too wish to share my condolensces with you. I am very sorry that your beloved pet has died.
Ginger and Kayla have mentioned a couple of possibilites and I would like to add a couple more for your consideration.
Did your dog get into the trash or regularly consume bones? How about trying to eat things he shouldn't, like socks or underwear? Did your veterinarian take x-rays?
Addison's is certainly a possibility...
There is a possibility of Parvo,Even sometimes when they have been vaccinated.Did his feces have a real foul oder.That is usually a give away for Parvo.It causes all kinds of GI problems.My condolensces for you.I am really sorry that you lost your Fur baby so quickly.
Parvo is a horrible disease. It nearly killed my dog just before I rescued her. And it killed all her puppies (the 'owners' had not bothered to innoculate her) It was a marvel that she survived, and I thank the vets who treated her. When she eventually recovered she was like a skeleton, and needed a lot of care and good feeding.