Help! Just published and now formatting is all screwed up

I have never seen this before, but I just published a post, and the formatting is all screwed up. The post that was published prior to this one is now taking up my right sidebar, but only on the home page.
There is also a lot of grey background where there shouldn’t be.
I have looked at the HTML source, but can’t find what might be causing this awful formatting!

Any ideas? Very thankful for any help.

site: lifeslittlebits.wordpress.com