What Causes Headache While Having Pneumonia?

I was diagnosed with pneumonia last Thursday after xrays were taken. I am on an antibiotic. I was scheduled today for a CT scan but don t know the reason for that or the results yet. I have all the usual symptoms and have had pneumonia before. What I have different this time is a severe headache that nothing seems to alleviate. I am 69. Is a headache like this usual? Thank you.