There are two classification 1.primary 2.secondary. in primary causes being allergic to coldness.smoking can intensify it.partly hereditary in secondary there are alot of reasons like PE,SLE,RA,non selective B blockers.
Reynaud's vasospastic phenomenon..may be associated with exposure to cold tempr ... if left untreated may lead to ischemia,gangrene
maybe bad circulation??? Maybe u should drink more water or eat more vitams