In this cold climate with electric heat, and since I'm around old folks, in and out of hospitals, my hands and fingers crack, spontaneously. I use polysporin on them three times a day, and try to keep hand cream beside every sink and in my purse. I have three of these hard to heal
openings on my right hand, I am right handed. I don't know exactly where they came from but they are slow to heal as they are constantly exposed to soap, water, dry heat and cold. Sometimes, I wear cotton gloves over well moisturized hands at bedtime. Good luck.