Linda - There would be several things going on.
1. HOrses compensate for injuries, so finding a problem in the RF after an
earlier injury to the LF isn't surprising since the horse has shifted a lot
of weight onto that limb to take it off the other. That may be all that is
wrong but now you have 2 injuries to deal with.
2. On the other hand, since she did the splits in the pasture, she should
well have hyperextended lots of things.
If there is heat, a vet's advice would be first on my order of treatment.
I would also want a good assessment of the extent of the injury, especially
because of the "split" episode. Massage can be great but it can also be
damaging done at the wrong time during the healing process.
Cheers, Laney, Certified Equine Body Worker