Well that all depends where your sights are set. If you're want to stick with web development I suggest learning to work with some sort of content management system (Drupal, Wordpress, etc.) Many of them are coded in php with some Javascript sprinkled in here or there, so you don't necessarily have to "stop" learning php, learn to use it in some other way and add another skillset under your belt.

Or you could look at Java or C# for platform development, they're pretty much one and the same thing only that C# locks you in with Microsoft, so Java imo is the better option to go with.

There's also always C and C++ if you feel like getting down and dirty with the hardware itself, so it depends. Ask yourself what you want to do and go from there, that way you'll get much more solid advice from people.