Did you take her temperature?
DO NOT SWEAT IT. Take her temperature. If it is elevated CALL THE VET. Your horse could have cellulitis which is an infection of the deep subcutaneous tissue of the skin. When left untreated by antibiotics it will kill your horse. I have seen 2 horses die from seemingly small untreated cuts because of cellulitis and the horse going septic. The vet will probably put your horse on antibiotics and/or NSAIDs and tell you to bandage the area.
If her temperature is not elevated, then monitor it. Take it twice or three times a day and if you get two abnormally high readings in a row then call the vet. In the meantime, cold hose it and remove any and all scabs. Then wrap it well with a stable bandage, I recommend putting guaze over the wound and a topical like Polysporin to make it easier to remove and re-wrap. You need to keep it very clean.
The problem with sweating a leg is that you are getting rid of a useful symptom. Legs don't just swell because it's a fun thing to do, they swell because something is wrong. When you remove this symptom then you are removing the indicator that tells you if things are getting worse or better.