Hi Viv. Some of the features of your headache do suggest the possibility of a CSF leak. This can be patched, but you would need to see a neurosurgeon.
I see you are offline.
I will check back a bit later.
The procedure for fixing a CSF leak is called an epidural blood patch.
To look for the leak, you might need a CT myelogram or radionuclide cisternography.
These would be questions you would want to ask the neurologist about.
Let me know if you have any follow up questions about this.