I Have A Recurring Cut At The End - Tip

I have a recurring cut at the end - tip of my nostril. It is not a sore and not inside my nose. It is like my nose tip splits! It happens more in the cold weather or if I am not getting enough rest or if my blood sugar levels have been high (I am diabetic but in generally good control with A1C consistently under 7). I've tried using Aquafor ointment as recommended by my dermatologist, but it has not helped.