May I ask what known troubleshooting steps have you tried already regarding 522 error for your Website? 
Was anything lately changed on the origin host/server or with firewall?
Does it work fine when Cloudflare is temporary Paused?
- Use the “Pause Cloudflare on Site” option from the Overview tab for your domain at dash.cloudflare.com .
- The link is in the lower right corner of that page.
- Give it five minutes to take effect, then make sure site is working as expected with HTTPS without any error
Is the origin SSL certificate still valid? Is your web server still listening to 443 port?
Are Cloudflare IP allowed to connect?