A concussion can last for weeks
after the
head injury. The symptoms too vary from person to person. Headache, confusion, memory loss, dizziness, nausea vomiting, slurred speech and fatigue are common. Delayed symptoms include depression, irritability, sleep disturbances, seizures, loss of smell etc. Injury to olfactory and lingual nerves of smell and taste could be a cause or it could be that nerves are in shock.