Strange Characters are being added automatically

Need some serious help. Trying to figure out the problem from last couple of days but still can’t manage to get a solution.

Some strange words are adding automatically to all links in my site, Many tools and Google bot failed to crawl those links and i’m getting lot of not followed and Not found errors in Google Webmaster tools.

Example:
Response Code: 302
Fetched URL: http://www.geekdashboard.com/
Final URL: http://www.geekdashboard.com/TSdPZ/

Response Code: 301
Fetched URL: http://www.geekdashboard.com/nokia-lumia-625-largest-display-family/
Final URL: http://www.geekdashboard.com/RZhNZ/nokia-lumia-625-largest-display-family/

Can someone please drop me a suggestion for this issue
Thanks