<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been having a constant frontal headache for the past few days. What could be the reason behind it?  <response>: Well, one of the reasons for your headache could be due to your primary immunodeficiency. This condition leads to a weakened immune system, making you more susceptible to infections, which can cause headaches as a symptom. 