Triple H is not suffering from a legitimate injury and the ending of WWE Monday Night Raw was completely scripted. While I haven't heard where they plan on going with the angle, the belief is it's some type of concussion angle where his family will try and convince him not to wrestle again. You can view footage of Hunter after Raw went off the air here on dot com.
I speculated in Ask WNW that Hunter would be off TV following Extreme Rules, however, he clearly stayed on to further the angle and work Curtis Axel's debut.
Axel has a lot of support backstage and WWE is hopeful he catches on quickly.