When did that start happening? Because my blog also lost a lot of traffic from Google. It started from 25 May 2018. After that decrease, I migrated to HTTPS and further decreasing. But I immediately updated almost a hundred articles until today, and no significant improvements. There are also a lot of people out there who lose traffic too. Seems it has been a Google dance time. Let's we see what could be happening in one month.
Check your backlinks. There's a chance you lost a valuable link to your site or a competitor overtook you in the rankings for a particular keyword that generates traffic for you. There's also a possibility that a recent algorithm change is impacting the rankings.