I understand your concerns.
You asked a very good question.
Besides the financial reason, you are also very busy person because of your demanding job.
You have headcache for last 1 week with associated nausea, vomiting & dizziness.
I assume your doctor already ruled out high blood pressure issue.
These symptom can be caused by viral infection.
Sinus infection is another possibility.
Hence this should be treated with antibiotic & nasal spray if present.
Although you do not have any fever, on a more serious note cerebral venous sinus infection can cause these symptoms. This is relatively uncommon condition, but should be considered when headache does not respond to analgesics as you tried.
Intracranial bleeding is another possibility.
Cerebral tumors like meningiomas although less common, should be part of differential diagnosis.
Based on the above possibilities, a CT scan is a logical step.
A CT scan with contrast is preferable to plain CT scan.
I hope nothing is serious, but CT scan is required at this stage.