There could be several causes of the sores you are having - the most common is picking the nose
or trimming nasal hairs - which leads to a staphylococcus infection
. Other causes include cold sores due to herpes, impetigo, nasal polyps, lupus , etc.
Nothing can be said with surety without having a look at the lesions and without a proper clinical examination.
It would be best to consult an ENT specialist and rule out the possible causes and find out the confirmed diagnosis in your case.