New shoe question!

My toes were coming out of the sides of my old Under-Armour shoes so I gave in and replaced them with a pair of NikeFree's... First of all let me say I LOVE the shoes!  It's a completely diferent kind of running but it feels great and I'm going faster!  The only problem I am having is severe ankle pain on the outside of my left ankle... It's only on the left, and I can't figure out if it shoe related, or if I have done something else to it that I can't figure out...  I know the first day I ran in these shoes I pushed it too far and when I slowed down I started striking mid-foot to heel and it wrecked my knee (which I should have known it would and should have backed off), but this ankle pain is persistent and won't go away... I don't wear the shoes just to walk around in, only when I am running... Has anybody else had similar problems?  And what is my best course of action?  Would an ankle brace help?  I'm still forcing myself to work on it, I don't know if thats a mistake or not, I just don't want to lose training days...