How can i find out if someone put a hidden camera in my room?

Not too long ago I would have said you are too paranoid. Now, in today's world, you could be right. I like the previous poster's suggestion. If you do something ridiculous enough, whoever put the camera there will not be able to keep their trap shut. You could also have a look around the room and turn everything around that might potentially have a camera. It would have to be wireless, so if you have a friend with a radio frequency scanner and a knowledge of what frequencies it would likely use, you could try that. On the other hand, maybe you are just being paranoid.

Do something super ridiculous, and see if they confront you about it. Like pretend you are keeping somebody prisoner or something, you just need a friend to voulunteer :P