Robben, 35, will end a glittering 10-year spell at Bayern when his contract ends this summer, and had hoped to return to fitness in time for a fitting send-off.
Yet on Thursday, Robben admitted that his hopes of playing a final competitive game for Bayern are fading.
“I have my concerns, and I am not sure if I can play for Bayern again this season,” he told Sky Sport News in Germany.
The Dutchman has not played for Bayern since their 5-1 Champions League victory over Benfica last November.
After an initial thigh injury, Robben was set to return to action in January, but remained sidelined after further problems with his calf.
In February, he had an operation to remove two infected teeth, which were reportedly identified as the root cause of his injuries.
Yet six weeks on, the Dutchman is still not fit to play.
“It is frustrating to not know what the problem is,” he told Sky.
In a decade at Bayern, Robben has won seven Bundesliga titles and four German Cups. In 2013, he scored the winner in the Champions League Final against Borussia Dortmund.
His future plans after leaving Munich remain unclear, but he has been linked with a return to his home club Groningen and a move to MLS club Toronto FC.
“Of course I have had a few calls, but at the moment I just want to make sure I am training again over a long period of time,” said Robben.
Download our app and read this and other great stories on the move. Available for Android and iOS.