My SEO is getting hammered suddently

Hi, all

I'm in a quite frustration situation, and I hope some of you can help me figure out:

I've recently build a webshop at

www.billig-alarm.dk

which is still under development, although it is in its final state.

ProblemMy rank has from the start been around 20-40 on google on the chosen keywords, and slowly moved up. But all of a sudden, I am getting hammered by google - roughly on the same day, my rank has diminished by 30-50 ranks down on many keywords. Only thing I've done in the time is setting canonical links on products and built two link to my site (weak links though)

I seriously dont get why my rank is getting beaten down. Can anyone help me to figure out what could cause this?

Best regards Jesper