Yeah, no idea what it is. I recently took a train ride from Chur to Poschiavo and it was fine. And I also took a train ride from Zurich to Bern which was fine with me. But the few times I was on a train ride from Zurich to Lugano, I got some sort of severe motion sickness symptoms. The same thing happens for example when I take a train from Barcelona to Sabadell. A Renfe employee once told me that it could be the fumes of the breaks combined with the A/C fluids. It's also happened on the SGR Madaraka express train from Nairobi to Mombasa. Does not happen on Australian (was a kid when I last rode one) or the few Asian trains I've taken. Amtrak also seems to be fine, DB is fine (if you're lucky enough to catch one). No bloody idea.

Weird but life continues. That's why I now rent a car at Zurich airport and drive it to Lugano or catch a ride with a friend .