I'm a pilot, not a doctor.
After two weeks, you really should be having a broad-spectrum set of blood tests.
What age are you? Any other symptoms of glandular fever? Are you sweating?
Are you sure the headache is 'global' ie not localized like sinus, which even with a bad infection tends to be at the front and top of the head.
Odds are your body will beat this by itself, but it really should be given some help with this level of discomfort. Press for more tests.