So I had a customer early pay me in BTC and I am somewhat new to using btc but not like new new. I got payed around 1:12pm on 3/27/17 gmt -5 time and it is now 11:30pm 3/27/17 gmt -5 time. and there are 0/3 confirmations and im starting to wonder whats going on. I am wondering if the person double spent the btc. I don't know how that works but I heard people do it. Can someone please help me out.