I've been dealing with the same situation. Although I have no idea what happened, I did find a workaround to see the analytics for these past few days while this is down. When you're in the Trends tab, go to the left-hand panel and click on Units (or any other preferred statistic) and then adjust the date setting to "last 24 hours." The panel beneath the graph should also show you data for the previous 24 hours, so for now you can still see your recent analytics for the past 2 days. I can barely find anything about this online and it worries me.

Oh hey it's working again!