I'm so sorry about your dogs. My first dog, a pomeranian, also died of the same symptoms. Vomiting out of nowhere...(vomit can either be whitish or yellowish). This is a sign of being POISONED. Things like insect sprays, floor wax, paint, etc.. can usually cause this to happen. My dog, Autumn, didn't survive her poisoning of the kidney. (Poisoning usually leads failure of kidney functioning)
You may have a-once-not-so-happy experience with your dogs doesn't mean that this will happen to your future-doggies. You just have to be more careful about things that may poison dogs. Read about them & try your best to keep them out of those things. I may have lost my Autumn then, however, I am happy with my dogs now. I am really careful about those things now. Coz I know the feeling of losing someone close to you--such as a pet or worse two of them.
So, I would like to encourage you to have pets again. They would help you heal. Really. Hope I have help somehow. God Bless!!!

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e.m.s.