i would suggest separating her, put her in the dark to keep her calm, make sure she eats/drinks/
Inspect the legs for any cuts/scraped that could have become infected - if you find any infected area wash out the area with a weak saline/salt solution and spray the area with iodine and wrap in a bandage. If there is no 48hr improvement, take her to the Vet or the dreaded PTS option.
Failing to find any infection check for any hot, solid swellings, particularly around joints, she may have fractured/broken a bone or a similar sort of injury(tendon, ligament etc). if so you could try home splinting - two lollypop sticks or similar either side of the leg, and taped round tight keeping the leg straight, and bandaged. but the best option would be to visit the vet (or PTS), this will ensure any hypothesis is correct and deal with is accordingly, they can also assure the best bone line up etc.
make sure to keep her calm and immobilised if poss (cat basket or similar), check she is eating/drinking as normal as possible.