Can you tell us all a bit more? Is it Is it vibration/twisting or more of a shimmy? Is there any noise associated with it? Turning, does it get better or worse? Could be wheel bearings, steering head bearings or something as simple as an out of balance wheel, any leakage at the top of the fork oil seals?
Treat everything in life the way a dog would- if you can't eat it or foc it, forget it.