What should i do if someone is following me in a store?

Okay.I was at Wal-mart shopping.I needed to buy chocolates for valentines day so i went to the area where they sell chocolate.Then there was this man and he was looking at me. i got my chocolates and went away. i went to the area where you can buy movies,games, and gadget stuff.i turned around and that man was right behind me! I went to the bathroom and when i got out he was still there. I walked to the makeup area and look at some makeup products then all of a sudden out the corner of my eye, he was 5 ft. away frm me looking at makeup products.I looked at him and then he looked at me back. Wtf. i went to the back of the makeup area and looked back and he was gone. i started to go to the cash register and i notice hime following me and looking at me again!! I hid in the women's cloths area and called my dad to pick me up.I stood there and waited trying to find him..i saw him again and try to stay away frm him as possible.Then he was gone all of a sudden. I bought my products and waited for my dad. I tried to find him but he was gone. HELP ME! WHAT SHOULD I DO????????? Thanks.