This is my first time experiencing this kind of thing,...

This is my first time experiencing this kind of thing, so perhaps someone can explain it to me. Last night, I executed my sell at 0.72525. But the moment it enter, it went straight to enter sell at the bottom. This makes my whole account turn red and the margin level negative. It finally went down, and I decide that I want to close Breakeven, I was close in +1/2 pips, but the result is showing -8 pips with a loss. I already checked with ICMarkets but their answer doesn't really explain what was happening.