I'm sorry to hear you lost your Chloe so suddenly. My friend lost a very young kitty very suddenly and she also couldn't afford a necropsy. Jeremiah most likely had a heart problem that took he quickly. A kitty I adopted died from a heart attack a few years ago. Poor little Beau had such a hard time before he was rescued as a tiny kitten. My guess is maybe Chloe had an underlying heart problem that wasn't detected.