I noticed that someone said there might be a language barrier? In belize their first language is english, then spanish (my family originates from belize)
Anyway, to the OP
without saying what's been said; i'm sorry for your loss. I think put it into perspective one raisin for a dog is like a handful for us. The size proportions are different. It sounds like it was the raisins, but once again the only way to know is necropsy.
To prevent this from happening again, well don't feed your dog anything that isn't made for dogs. I'm not saying they can't get a little snack, but if it doesn't say it's for dogs (and even sometimes when it is for dogs it's not healthy) then you should look it up. It takes 5 seconds to google something before you feed it to your dog. Just some friendly advice.
I wanted to post this to kind of help clarify to those who don't know anything about Belize:
Also, I have family (and I visit yearly) in Douglass Village, Orange Walk, Corozal, San Pablo and San Pedro. San Pedro, being that it's more "touristy" has the best vets. My cousin takes her dog to a vet on that island and it's only a short flight from Belize City. Maybe you should look into where your vets are located. I know there aren't a lot tho. Belize itself, is not an island tho so I assume you're on one of the islands like San Pedro/Ambergris (which is so small you can literally ride a golf cart to each side), or Caye Caulker.
Like I said since these are more touristy they do tend to have a large degree of better medical care for people and pets
Once again, im very sorry for your loss