Any substance that interferes with natural brain chemistry can have very harmful effects, even leading to psychosis or seizures. Part of what constitutes brain injury is damage to chemical neurotransmitter production and pathways. Only a physician should prescribe medicines that can help provide the appropriate balance of neurotransmitter chemicals. Don't use them. They will most likely make effects of brain damage worse.
Headaches can occur because of many different problems.
Headache is one of the most common complaints following head injury. Usually, a headache is not coming from inside the brain. Usually, but not always, it is due to neck or shoulder injury, to jaw joint problems, general muscle tension, or to the sensory changes from severe cuts on the scalp. Headaches can be due to blood vessel changes within or outside the brain, in either case caused by head trauma. Headache is a complex symptom that should be brought to the attention of a physician.