Google has stopped indexing my site

Hi everyone,

All of a sudden it seems google has stopped indexing my site pages or just significantly lowered my page rank. I was ranked in the first page for a lot of phrases and received quite a bit of organic traffic daily but today I an barely ranked on the first page for “find your whey” the name of my site.

I am using the all in one SEO plugin and also the site map plugin.

My site: http://www.findyourwhey.ca

Thanks for any help with this matter
Tyler