I have php 5.5 with Sphinx pecl extension installed and it was working fine but it's not working any more after upgrading php to 5.6.9.
I tried to uninstall the extension and reinstall it but nothing changed. I also tried to reinstall libsphinxclient-dev but again, nothing changed.
I'm using ubuntu 14.04
Just ditch the extension and use sphinx-api.php. There really is no benefit to using the extension, and plenty of disadvantages (like upgrade troubles)