~The most common and least serious type of traumatic brain injury is called a concussion.
What is a concussion?- A concussion is most often caused by a sudden direct blow or bump to the head. The result? Your brain doesn't function normally. If you've suffered a concussion, vision may be disturbed, you may lose equilibrium, or you may fall unconscious. In short, the brain is confused.
Can children have concussions?- Because their heads are disproportionately large compared to the rest of their body, concussions often occur in young children.
Symptoms- Signs may not appear for days or weeks after the injury. Some symptoms last for just seconds; others may linger.
~Confusion or feeling dazed
Clumsiness
Slurred speech
Nausea or vomiting
Headache
Balance problems or dizziness
Blurred vision
Sensitivity to light
Sensitivity to noise
Sluggishness
Ringing in ears
Behavior or personality changes
Concentration difficulties
Memory loss
How to treat a concussion- Seek medical attention. A health care professional can decide how serious the concussion is and whether you require treatment. If you have suffered a concussion, wait until symptoms are gone before returning to normal activities. That could take several minutes, hours, days, or even a week.
Source- http://www.webmd.com/brain/concussion-traumatic-brain-injury-symptoms-causes-treatments