Why is it that i feel nauseated after hitting my head?

Brain senses it: Nausea, like all other sensations, is really the brains interpretation of inputs from throughout the body. The nausea centers in the brain are commonly disturbed in a head injury. Watch out for progressive/ worsening nausea - could be a sign of something causing increased pressure inside the cranium, and needs medical eval.

Eval: Symptoms of a concussion can include: headache, nausea, vomiting, confusion, blurred vision, slurred speech, weakness, feeling dazed, numbness, lack of coordination, problems with short term memory, dizziness as well as repeating things over and over. You can develop a concussion with or without loss of consciousness. It may be prudent to be evaluated.