Last week i let my horse out on the pasture.and he has got a big sore on his leg.there more info below.help!?

Now this pasture is completely covered in barbwire.Its my neighbors and they have cows so they don't care.But anyways he must have gotten in it cause iwent to go ride and he had this smallish puncher-womb on his left front leg and is on the outside of the leg below the knee.Its deffentaly not broken cause he will put dead weight on it.he also lopes on it.It was swollen bad for bout 3 days and it is slowly going down.i love this horse hes great.he a championship barrel horse and i just need 2 no what will help the swelling go down.and the sore to heal.please help me i love him and ant wait to start riding again.