It could be Raynaud s disease . The cold causes narrowing of small blood arteries supplying to your fingers and toe nails. It can be associated with many diseases, specifically of connective tissue, and current medications if you are using. You need immediate evaluation by a physician as I see many patients of Raynaud s disease come to us after having ulcers with blood oozing. So don t be late. The remedy is that take cold as allergen and avoid it as much as you can. Wear warm gloves and warm socks when you go to cold. If not corrected only by taking care of cold then use first low dose of Aspirin (acetylsalicylic acid) then your doctor may advice you as per your case severity: the Ca channel blockers (like tab. nifedipine). Don t be worried. It is well controlled just by avoiding cold.