I have heard the cold air thing as well, a previous BB member had to call an ambulance for her son who was really bad one night and they took him straight outside in the cold and it helped right away - not exactly sure how it works.

Jols how long does the predmix take to kick in? If it's relatively quick you could try everything else and if nothing is working or she's getting worse you have it there as a worse case scenario ITMS?