From Wiki - this sounds like what you've got. Hubby used to get the same thing on his scooter.
Vibration White Finger (
VWF) is a secondary form of
Raynaud's disease, an
industrial injury triggered by continuous use of vibrating hand-held machinery. Use of the term Vibration White Finger has generally been superseded by
Hand-Arm Vibration Syndrome or
HAVS. The symptoms of VWF are the vascular component of HAVS.