Migrating to SSL can cause unexpected side effects. When caching is causing redirects, or a plugin redirects back to http, or other such issues, it can be helpfull to activate Really Simple SSL in a minimized way (as of 2.5.9).
First, deactivate Really Simple SSL (use the remote script if you don’t have access to the admin), then, add:
to your wp-config.php.
This way the plugin won’t:
- change your site url to https
- add a redirect
One thing will still be active, which is the mixed content fixer. you can disable it in the settings, at which point the plugin is not actively doing anything.
If your issue doesn’t come back in safe mode you can try to enable the features one by one, mixed content fixer, add a redirect (settings/ssl) and change the url to https (settings/general) separately, so you can narrow down which one of these causes the problem.