Absolutely no offense meant, but I know a few folks who use the crystal deodorant and it really doesn't prevent odour! Maybe they don't use enough of it?
Anyway - I am also highly allergic but you can find non-scented and hypoallergenic deodorant now which seems to avoid the problem. You can use a cortisone cream to clear up the rash pretty quickly.
A steroid cream should help the rash.
I have found the best deodorant and it is all natural. My dh cannot use deodorant because he gets huge boils (tmi)that hurt him terribly. My brother works for the phone company(out in the heat) and started using an all natural mineral salt deodorant. I bought some around christmas and it is the only thing I will use now. Dh loves it!!! It doesn't break him out and takes care of any bo. I found it at Wal-Greens, costs 4 or 5 dollars but lasts a year.It's called naturally Fresh Deodorant Crystal. Maybe you could try it when you get your rash cleared up.
Zinc cream.
And swithc deoderants
Maybe a rash cream designed for rashes??