It is true that withdrawal bleeding is often seen after taking the emergency pill, but, itching is not a side effect. You are perhaps having some vaginitis
which needs to be treated, your partner also may need treatment. Since the bleeding is decreasing in intensity, you may wait for it to subside on its own. If it does not do so in a couple of days, you need to get expert help in person. If you are due for your period, it is possible that you have had a menstrual period also set in. Please see a specialist for further help. Hope this helps.