Hello... In some people external stimuli like cold or any temperature variation can cause blood vessels in your leg to constrict resulting in pain. It can occur without any reasons, but in some it occur as part of autoimmune diseases. So it is important to workup for such autoimmune diseases. There are medicines which can help to prevent extreme constriction of blood vessels.
Next Steps
patient should check Antinuclear antibody test and ESR
Health Tips
Peripheral warming of legs are important.