Just to give a follow up to this thread:
I also heard from a friend to go to Chris in Affoltern, so that was two votes there.
I wound up going somewhere down the street from my house in Birmensdorf,
http://www.mouwen.ch/.
As I have now gone there a few months I wanted to recommend them and add to the EF list of English speaking physiotherapists. My back is completely sorted and I am very happy with them.
It is kind of a schlep in public transport- the bus in front (Weissenbrunnen) is only every half hour, and otherwise it is a 15 minute walk to Birmensdorf Zentrum or 10 minutes to Birmensdorf ZH Bahnhof, so it isn't great it you are on public transport and crutches, but if you need physical therapy for back stuff, I actually enjoy the walk after my back has been all stretched and pulled. Parking is available.