Clear Cache and Cookies for All Websites
Tap Firefox Menu Icon
Tap "Settings"
Tap "Clear private data"
Unselect call check boxes except the following:
Tap "Clear Data"
Close and reopen Firefox
Clear Cache and Cookies for doxy.me only.
Repeat the steps on step 3-4 click recently visited sites.
Find doxy.me and swipe to the left and tap delete