Any time you have a headache from being hit in the head, it is likely you suffered some degree of brain trama. The question is how much. Given it has been a week and you felt nausea, that tells me it requires paying attention to. Your best bet is to stop sparring for a while atleast...

As far as brain trama goes : Traumatic brain injury - Wikipedia, the free encyclopedia

Here is a list of symptoms to look out for. Not enough boxers are aware of them, or their trainers for that matter, but should be.

Mild TBI

-headache
-mental confusion
-lightheadedness
-dizziness
-double vision, blurred vision, or tired eyes
-ringing in the ears
-bad or metallic taste in the mouth
-fatigue or lethargy
-a change in sleep patterns
-behavioral, personality or mood changes
-trouble with memory, concentration, or calculation
-decreased coordination
-symptoms may remain the same or get better; worsening symptoms indicate a more severe injury

Moderate or Severe TBI

-loss of consciousness
-personality change
-a severe, persistent, or worsening headache
-repeated vomiting or nausea
-seizures
-inability to awaken
-dilation (widening) of one or both pupils
-slurred speech
-weakness or numbness in the extremities
-loss of coordination
-increased confusion, restlessness, or agitation
-abnormal posturing, ie. decorticate or decerebrate posturing
-vomiting and neurological deficit (e.g. weakness in a limb) together are important indicators of prognosis and their presence may warrant early CT scanning and neurosurgical intervention.