Oh, OW! For three weeks, use whatever you already own. Just don't try to use a shoe with aggressive tread with the platforms. You may find that the treads catch and settle into a certain angle on the pedal that isn't good either. Firm but smoother sole so your feet can sit anyway they like until then.

Maybe wedges or orthotics will help but don't spend money until you talk to your PT.
http://www.slowtwitch.com/mainheadin...t/lewedge.html

Hang in there.