Sores in the nose are usually just the common cold sore which most commonly occurs on your lips but cold sores can also occur inside your nose.
It could also just be a dried out nose as well and keeping your nose moist or washing the inside of your nose with a saline solution can sometimes help keep cold sores from appearing in your nose.
The cold sore is also caused by the herpes simplex virus so keeping up on Vitamin C can also help prevent cold sores and other viruses.