stolen credit card number

This past Halloween my credit card number was stolen. Discover was really good about calling my home phone in NOVA but they wouldn't tell my mom any details because she's not me. Of course she was concerned and tried calling me right away. Earlier in the day I missed a call from my mom and I was away from my phone again when she called about the credit card. Her mind went into Mom-mode and freaked out. She thought I had been kidnapped and someone was forcing me to use my card. I was eventually able to get back to her and calm her nerves.
The guy charged $750 on my card at a Winn Dixie and Office Depot. Funny thing is, I have a pretty low credit limit because I'm a student and it's my first card. Therefore they overdrew my card and got caught right away. It was comforting that Discover jumped right into action but knowing that someone was still able to get my number and use it in person at two different stores is unsettling.