On Monday, my lips became very dry and I felt the center of my lower lip split open slightly. A red sore developed there. I was concerned it was prodrome for a cold sore, which I have had before, but it never blistered, filled with fluid, or ulcerated. It is now Saturday and the red mark is slightly smaller, but still there. It stings if I don't keep it moisturized. Is this just severly chapped lips/the split healing? Can it be a cold sore even if it never blistered after five days? I am only concerned that I don't kiss my boyfriend if it is a cold sore. Thank you for any advice.