I found out that someone's been using my card since yesterday. They went to Longhorn steakhouse, target, Walmart, a fabric store. How do I get them to stop using my back card? I think someone at McDonalds scanned it or maybe took a picture of it. I really need this to stop.

Call your card company immediately, they deal with stolen cards all the time, often they will identify an unnatural usage pattern and call you.

Typically there card company will refund you after an investigation and just give you a different card#, they often write off the loss and don't pursue persecution as hard as they could. (They are the ones who can compel the merchants for information)

Put your sister in a chokehold and make her confess ... because usually a person needs a PIN.

EDIT: You are a 15 y o girl wondering about starting ballet while rooming with a female friend and attending college, and have a bf who's parents are racists. You are either a very remarkable young woman, or a TROLL !!

Call the Bank immediately, as in this instant! Tell them to cancel transactions from that stolen card and report it before it's too late!

bacon