Acute mastitis with headache even after the fever has gone down can be caused by a buildup of milk in the breasts, inflammation that interferes with rest leading to head pain, or craniosynostosis. Acute mastitis would have been accompanied by fever and headache. Fever is caused by a pathogen infection, the immune system works, and the pathogen produces a fever activator, a substance that causes the patient’s body to produce an increase in body temperature. After the fever subsides, the headache may persist and continue to be relieved by treatment. Headaches can also occur if you don’t rest well, so pay attention to a light diet and get enough sleep. If rest does not relieve the pain, you need to consult a doctor in time to check whether it is a craniocerebral disease, such as infectious meningitis, encephalitis, etc., will also appear headache manifestations, may be mistaken for mastitis caused by the need to clarify the cause of the disease.