Hoof and Foot Health

I have a mare who has some lameness in her front right foot.  It started after I put her on some new pasture..she was out there for 2 days before I noticed she was laying down.  I thought she foundered but the vet said no and suggested a foot trim.  I trimmed her a couple of weeks back and noticed some cavities and holes in the hoof.  I finished the trim and her foot is still tender, but she is stalled and doing well.  I'm turning her out one hour a per day, per vet's instructions.  I noticed today that she was putting her foot into the water trough...Question, I don't know what the cavities are and does it have anything to do with the trough thing?

I'll get one in the next day or so.  I've increased her turnout time and she appears to be doing better.  Hopefully, i'll have you a pic by Friday.. thanks for the reply!

I guess she is doing better. Without the pictures I would prefer not to guess but for the benefit of discussion, I believe that it could be a sole fungus which I would treat much like thrush or white line disease. I have been called out on cases where the horse had pits that have penetrated through the sole and I have added a shoe and a medicine pad. Treat a cotton ball or gauze and push it into the cavity and replace the plate. I have had soles completely heal over in one trim cycle before.