Help with domain

I hope someone can help me with this issue... I have a domain that is showing up with a hop extension on google (ex: mydomain.com/?hop=0). my rankings have dropped on certain keyword terms from being on page one on google to now being on page 3.

I'm sending backinks to mydomain.com. however it is still showing up with the hop extension. Anyone know how can I remove this hop extension...

Do you have a Google webmasters account with this site submitted?

yes I have a google webmaster account... but it's mydomain.com and not the domain with the hop extension.. that's why i don't understand why it's showing up in the first place.

Create entry in .htaccess and redirect your hop url to home url of site... Soon all link juice or search engine will be updated with it...