Over the past several 1-3 month trips to EU, I have developed a variety of food problems and injuries. Some are ok after a few days rest, but I got some severe nerve pinching in one foot, which persisted over 6 months after returning to the US.
I have tried half a dozen or more shoes, boots, and Birkenstock sandals. I have finally found some pretty ideal shoes. I don't know if its permitted to mention a precise brand name and shoe model. But what I found is that some upper end running shoes have "trail running" shoes which have firmer soles and knobbed bottoms which seem to work better on cobblestones.