Okay so I am selling my clothes oline with a friend, she left me incharge of the buisness while she is overseas and honestly I don't know what to do. 

So theres this person that wants to buy this bag for $15, they emailed me and they told me to give them my pay pal email adress. I did (I have no balance) and they sent me the money and I got an email saying I have sent me $130. It told me to send the $100 to their pick up agent for delivery via western union. The email also said I don't get it until I send the $100, and this email is an confirmation from pay pal and I got it in my junk email. I made an account on western union ready to send it but it wants me to use a credit card to send that $100. 

I re read the email and the person buy the thing is named Patricia Hempton but the email is  [email protected] and the pay pass email I got is reffering to the person as a 'he'. Also they want me to send the $100 to Nigeria, when I sell my clothes on an australian website. Can csomeone please help me out and see if this is a scam? What do you think I should do

Now the person is emailing me telling me I have to pay by credit card ASAP please answer