[Help] Fluctuating Rankings - Crawl Errors?

Hello,

I am new to the warrior forum and have been brought here because I am having some issues with a customer.

I have a SEO client and cannot work out why his website is fluctuating on his rankings so much.

With my own personal website we have had no issues and when improving in rank week to week we did not have much fluctuating.

Here is the rankings:


Can any one shed of expertise on what could be causing the rankings to fluctuate so much on a weekly basis. These keywords are not very competitive either.

The only thing I can see that could be causing it is crawl errors, There is some random errors that I cannot solve for example. the 4 errors the site has now its saying its linking from pages that do not exist so have no idea how Google is finding the pages plus I have checked the sitemaps to make sure they are not hidden in there.

One error is saying there is a page being linked from sitemap but when I check it is not on the sitemap?? This is a wordpress install and I did not build the theme so wondering if theres some major issues.

Any ideas would be much appreciated.