I have a white patch inside my left nostril? Is this normal?

DEPENDS. Most commonly these are apthous ulcers, the medical term for the white erosions people often get in their gums /inside their lips. This can happen in the nasal mucosa as well. Depending on your habits, or the humidity conditions or the status of your immune system it could be serious or something that will resolve with time.See your dr. And give your history so that you can get a clear diagnosis.