If the area is swollen, red, and sore, and the pain is going down your whole leg, you could have gotten an infection (cellulitis) from scratching it open. If it looks like this, you should see a doctor soon, since you may need antibiotics. Don't have sex until it's healed, since sex will irritate the area more right now.
The itching part could be yeast, but major swelling and redness would be a bad sign.
It's probably yeast. Try an antifungal cream and follow directions.
oh i mean it was itchy before i scratchd it now it is very sore i cant sit on a cold toilet sit since the pain cover the whole leg.the pain is like when u have fever whatever cold thing dat touches your skin feels painful