According to WWE.com, Seth Rollins re-injured his right knee during the Monday Night Raw ambush by Samoa Joe. Rollins is scheduled to undergo evaluation on the knee sometime this week.
Ryan Satin of Pro Wrestling Sheet has reported that backstage officials are currently working on a Plan B for Triple H at WrestleMania is Rollins is injured for the big event.
You can see footage of Seth Rollins leaving the arena on crutches after Raw at this link.
UPDATE: According to PWInsider.com, Rollins is currently in Birmingham, Alabama being evaluated. This is usually very bad news.