There may be other reasons but the 1 reason I am aware of for a ceiling fan to shake is that the tilt to one or more of the paddles have been moved so the fan is unbalanced. If you look at your fan you will see that each paddle is tilted at an angle, if they are not all tilted in a spcific way the fan will shake. It is very difficult to get them readjusted correctly. It happened to my fan and luckily I knew which paddle had been hit so I managed to readjust it myself. However, as I said, it was pure luck since I could have just as easily made it worse. Main thing is that until it is fixed you shouldn't use it since the shaking could cause it to fall if it is bad enough, as if the sound isn't annoying enough to keep you from using it anyway. I don't know if there is anyone you could call to repair it. Replacing it would be the safest thing.