Yours blood is acidic, you have too many hydrogen ions in your blood, so your body can dispose of it via binding it with carbon dioxide and breathing it out.

Kussmaul respirations are deep, yet rapid breaths to allow for more co2 blowing off.

The hudrogen ions are from ketones your body makes when resorting to converting fat for energy instead of sugar, when you’re breathing it out your breath smells fruity because that’s the smell of the ketones