Despite being involved in Bayern Munich's last three fixtures, Robben missed the national team's training on Monday and he is concerned that he is yet to fully recover from the injury.
Robben was quoted by De Telegraaf: "I am worried. It is definitely not good and it is annoying that I do not know where I stand."
The lack of a proper treatment for such injuries is a point of disappointment for Robben.
"It is a complicated injury. There is no one who can say exactly what you can do [to fix it].
I would rather have a torn muscle - at least then I would know that after six weeks I would be fit again."
Robben has been called up to the squad that will play against Moldova and Sweden in the last two Euro 2012 qualifying games, though it is uncertain whether he is fully fit to play in both fixtures.