UPDATE
As you know the vet comes out tomorrow, we soaked Luna's foot in epsom water yesterday and we went down to do it today. I met with LITTLE resistance this time to picking the foot up, and upon placing it in the bath I noticed a small knick on the front. She was more active last night after the bath so it is entirely possible she pushed the supposed abscess out, she doesn't appear to be limping today. I think she may be sore in her back end from the sliding stop the other night, we're having the vet come out regardless to check her over and suggest anything else but right now she doesn't appear to be in any more pain, she is putting weight on the leg, and MORE IMPORTANTLY it is no longer hot, or swollen and she didn't resist when I picked it out like she was doing before.
I couldn't see any pus, but she is out on pasture and it did rain so it is possible it got washed out easily.