In need for Help or some good advice

Hi there,

I have a webshop and for the past year I have had good rankings. only last month my rankings had dropped.
Lets say from 1 to 5 for main keywords. I am trying to find out where my problem is located. I see in rankerizer that in the time span my rankings dropped i got a huge increase in backlinks. I see this on rankerizer. I was not building any strange or blackhat links in that time period [see attachment]. After that i tried to figure out wat was going on.

In the past one year ago i used voltrank ; Ithought maybe that was the problem and deleted my links on that one 100 links to main keyword. now that keyword is not listed in top 1000 anymore and i used to be on spot 1.

I do not have any message in google webmaster tools and dont see any strange sites in webmaster tools so cannot reject backlinks.

Any advice or help on these to matters?
1. main keyword dissapered after stopping voltrank (maybe they deleted all backlinks at once)
2. drop in many main Keywords after increase backlinks [see attachment] I did not created the backlinks nor google webmaster tools is showing them


Any help is appreciated!!!