It needs to be properly managed so it does not become infected and turn into an abscess. The simple treatment is to apply ice pack or small piece of ice block wrapped in handkerchief on it intermittently for the first 2 -3 days. It will go down. Also avoid too much handling of the affected limb as the site is usually sore. It should resolve in 2 - 3 days but if it persists and/or become bigger and soft with pus inside that is an abscess, please go back to the Hospital or Health Centre so it can be drained and additional treatment including antibiotics will be given