This is an SEO request not about design.

I have spent much time trying to do "what Google wants". I have written weekly blog posts in my WordPress blog since 2006. I have tried to write useful articles for others in my niche and I have been rewarded with loyal followers.

Off-site I have only got natural in-bound links from people who like my stuff and I've only ever done maybe 10 guest posts. I also get natural social shares. I have never indulged in any paid links as far as I'm aware.

Ever since 2006 my organic Google rankings and organic traffic has been increasing, as you'd expect as I constantly add quality articles.

However, since at least the beginning of the year my organic traffic has started to fall to a point I now have the same traffic as two years ago!

This is quite an extreme drop of at least 50% of organic traffic.

It looks like I've suffering some Google penalty but, for what, I don't know.

Any suggestions? The site is

Thank you.