Lame cob, please help!

[bella-india]

Hi, my cob, Lucky, has been lame for a while now, and I've had a good look at her hoof. She has a cavity, which I'm pretty sure is benign, but I've flushed it out with hydrogen Peroxide just in case. The other thing is the bruising around her hoof wall, its pretty dark and she's very, very tender on it, and I was wondering if there was anything I could do to help the healing process, apart from give her 'bute to help with the pain?
Thanks!

[bella-india]

I forgot to mention that she is Barefoot and due to currently having a foal hasn't done any strenuous work at all. also, how long would a cavity the size of a AAA battery in the foot wall take to heal? cheers!