What Causes Sudden Outbreak Of Pus Filled Lumps On Nose?

My boyfriend hardly ever gets acne and last night out of the blue the side of his nose was red. The next morning tons of tiny puss filled pimples showed up. We have know eachother for a long time and I have never seen acne like this on him. Any suggestions why this happened or how it happened so fast? It s so unusual for him.