Theme Tour Package ruined my site?

Hello. My site, www.jasoerejser.dk, used to be ranked on page 1-2 on the chosen keywords until something happend a year ago. I changed the theme november 2014 to “Tour Package” and every since my ranking has dropped to page 9 (!). I have fully optimized most of the page, had SEO-people working on the site, but absolutley nothing happens. The domain is popular and from the 90’s, so now I kinda blame the theme for making it drop so crazy. But should that be possible?

Does anybody have any experince in this theme? Or has anybody experinced something likes this? The tekst, links, pictures and everything is the same as on the site in nov 14. But optimized with time.