Hi, The place where you hit your head is a common site for brain hemorrhage due to external trauma. Head injuries can range from just a bump on the head to bleeds inside the skull which compresses the brain. Since skull is a closed and rigid cavity with no extra space the blood collection starts creating pressure on the brain. This increase in pressure can manifest anywhere between 4-24 hours after trauma. Usual symptoms are headaches, vomiting, blurring vision, incoherent speech change in levels of consciousness. Overall it is a dangerous situation. However often patients after suffering head trauma experience nausea like you are due to anxiety. But I would urge you to get yourself checked and if an inkling of doubt please go for a CT scan. A word of caution...CT scans can also fail to catch bleeds too early as the bleeding might be very slow in blunt traumas and take time to collect and show up on the film. I hope you have a superficial contussion and nothing major. Please take care.