Thanks for the query.
According to your description the possibilities are:
leading to inflammatory signs due to the chemical content in the shampoo.
So better to consult gynecologist once, get examined to find out the actual nature of the discharge and take treatment accordingly.
And scratching should be avoided as you know.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429