A very common symptom following TBI is that of a feeling of dizziness or problems with balance. If this problem goes on for more than several weeks following your injury, you should go to an ENT (ears, nose and throat doctor) to undergo a battery of tests to determine the possible causes of the problem. Most balance and dizziness issues are due to an injury or problem in the vestibular system in the ear. If someone has, for example, a fractured temporal bone near the ear from trauma, that can give rise to these types of problems. Injury to the cerebellum in the back lower part of the brain can induce nausea and spinning sensations. If an examination of the vestibular area of the ear is normal, than your ENT may tell you that the problem is "central," which means that the problem is in the brain and not the ear.
Some of the things involved with this type of symptom include nystagmus, which is the involuntary horizontal movement of the eye as it gets toward the edge looking peripherally. If the eye shakes back and forth, that is indicative of a possible vestibular or central brain issue. An ENT can also give you a number of tests including the Hall Pike, ENG, caloric testing, and many other ways to determine the problem.
Be especially careful to determine if there is any leakage of fluid from the nose or ear following trauma. This means that there is damage within the ear or nasal area that is allowing CNS (cerebrospinal fluid) (CSF) a clear or pink (with blood) fluid that surrounds the brain and spinal cord. Any breach in the head that allows CNS fluid to escape poses a grave risk of various brain infections and needs to be addressed immediately.