For three days now i have had blood when i blow my nose. it's not bleeding out its just on the napkin. it's only in my left nostril. what could it be?

Epistaxis: A small amount of blood when you blow your nose is common, often from the irritation of sinusitis or an upper respiratory infection. It can be bleeding in your sinuses or from small cracks or irritation of the nasal mucosa (at this time of year, often from overly dry air.)

THE NOSE KNOWS!: Winter air is particularly irritating to the delicate tissue inside of your nose. The cold dry air interrupts the natural mucus that protects the tissue, leaving the thin, delicate blood vessels inside of the nose exposed and vulnerable to bleeding. These events are usually self-limiting. I would be happy to share additional, simple remedies with you via an inbox consult.