This sounds like a tension-type headache, your neck and head tighten up as a physical stress response when you feel pressure to perform during a call. It is not a sign of anything wrong with the brain or nerves, and relying on daily painkillers would only mask it rather than fix the trigger.
Next Steps
Try a few minutes of slow breathing and shoulder and neck stretches before each call, and keep early practice sessions shorter so the tension has less time to build. Since you already have raised blood pressure readings, keep monitoring it regularly, as stress can push it higher.
Health Tips
If the headaches turn sudden, severe or different from usual, or your blood pressure stays consistently high, please see a physician to review both properly.