A severe headache的用法和样例：
- I had a severe headache that evening.
- I have a severe headache, and my neck is stiff.
- John had such a severe headache that he'll have to go to see the doctor.
- John has such a severe headache that he'll have to go see the doctor.
- A severe headache, worse than anything you have ever felt, could mean bleeding in the head from a broken artery.