Thank you Sandra!
Let's specify: "having a strong headache finishing up my work tasks/client work and packing for vacation for my birthday. " So this headache came while preparing your vacation? You completed the work tasks with clients before the onset of headache?
To me it seems as if it comes on the tipping point between work and time-off, when the body anticipates the opportunity to restore (regeneration trigger). Then, you complicate things by perfectionism (added stress), so the headache forces you to take it slower.
There are different forms of headache, some of which are due to muscle tension belonging to rather defensive reactions and overthinking; other headaches feel more like pressure from inside and come typically after a stressful time, when the head wants to let go..
Good job in being aware of your drive to control and to push yourself in order to get closer to - safety?
Interesting that your birthday seems to be connected to this!