Ugh. That sucks, especially at her age. It sounds like you're doing everything I can think of.
The only thing I wouldn't do is turn her out until you get a hold of the vet.
And I've been battling a torn straight sesmoidean ligament in my (now 17 year old) gelding for two years. He was stall bound for 7 months in 2008 and was sound enough for turnout. Then got MUCH worse and has been stall bound since April of 2009. Absolutely NO turnout, as he's a kook. We're up to walking for 40min, trotting for 2min U/S; I heart acepromazine.

Here's hoping he's out of the stall by April... keeping my fingers crossed. And this was the "best case scenario"- at the beginning, our only goal was to get him sound enough for turnout. Now he MAY be a nice pleasure horse. Unfortunately he doesn't like being "just" a pleasure horse... sigh.