Although it was not my experience, people on the oxylist many years ago reported that long-term use of H2O2 (Hydrogen-Peroxid) did affect the stomach in a way that was not too positive. It is too long ago to remember the specifics.
I do know that H2O2, Homozon or even highly ozonated water will interact with many foods and I would think that the sulphur component of garlic would be one component that would interact violently causing gas and mild sulphuric acid. I don't know why it would still interact after 12 hours unless your system was very saturated with garlic and its compounds.
Was your ozonated water made with a medical grade machine with oxygen or just an air-fed ozonator? It makes a big difference.