Very true about keeping the clay wet. I should have mentioned that we had to keep soaking the cloth that was wrapped around the clay (and his leg) every 10 minutes or so for the first couple hours. It probably wasn't doing much after that.
I'd probably just use the liquid form in the future (kind of a creamy consistancy). It would be easier to apply and likely stay moist longer. I would do it separately from any other treatment in the same area because the clay will hoover the good stuff too.