If you take a look inside the control panel, you’ll see that your account received a MASSIVE hit spike. It was so big that the red limit line is basically at the bottom of the graph.
If I had to guess, I’d say it’s most likely that your website was the target of an attack. While actively using a site can result in high hits usage, it’s very hard to make the hits usage go this high.
Unfortunately, all I can do is guess. We don’t store the full access logs for your website, we only count the number of hits, so there is no way to know for sure what the traffic looked like or where it came from.