Side bar widget appearing at bottom of page

I have an issue with my WordPress making the sidebar widget appear at the bottom of all my posts. It seems quite a common issue and I’ve tried a few things suggested by others including enabling “WordPress should correct invalidly nested XHTML automatically”.

Does anyone have any insight in to what may be causing the issue? It happens on all posts on my blog. One example for you – https://www.alexwisephotography.net/blog/2013/08/18/melbourne-traffic-long-exposures/

Thanks in advanced for any assistance,

– Alex