The answer to this question would be viral meningitis.
Inflammation of the brain membrane(meninges) called meningitis. This description is too little to determine whether it is bacterial or viral meningitis but generally, bacterial meningitis will cause more severe symptoms like a seizure. Viral infection is often giving a higher fever too. A cerebrospinal fluid analysis might be needed for a more certain diagnosis. Both infections can spread into the brain tissue called encephalitis. When encephalitis happens the patient might lose consciousness. Edema in the brain can cause higher intracranial pressure that will cause a headache and nausea.
