Well the massaging/hosing/walking has helped and there's no sign of swelling anymore, but there's still something that's off about her. She doesn't have her usual arab alertness and spark in her eye. I took Luna out to work her for awhile and Stella did trot around and call for her like she usually does, but there's just something different. I'll be having the vet out asap.
With the grass I'm always aware of colic and founder and try to monitor their intake as best as I can. Onetoomany, thanks for the heads up on other possibilities. :)
Thanks again to everyone for the input!
Stella - sweet, timid, elegant, lovely, lively, amazing
Luna - large, unattractive, naughty, adored