You wouldn't have memory loss from a hit to the nose. If it were stronger and higher (probably from another angle) you could have hit the brain, but now nausea is probably due to hitting the many nerves that are in the area. You might have had blurred vision and feeling dizzy for a bit after the impact with the ball. It's perfectly normal. As long as you remained conscious and have no deep cuts it is unlikely to be any serious damage.
What Jerry said has a basis, but only if you experience difficulty in staying awake. So, sleep well and don't worry. If the problem comes back tomorrow go see a doctor.