Hello -- I note you've had MRI of the brain done, so am wondering if you've seen a neurologist in regard to this problem. While the other rule-outs made sense as starting points, the thing may be a little more complex, especially since you find manual pressure on your head can aggravated tenderness and you have visual disturbances. I'm thinking there may be some problem with one of the cranial nerves, perhaps inflammation due to a virus. You actually could have the occular form of herpes simplex/shingles, and while this is sometimes difficult to determine in the general practice setting, a good neurologist should be able to uncover it if present. This is my best guess based on what you've mentioned here, and it does happen, although it is relatively rare. The visual disturbances and scalp tenderness does strongly suggest occular herpes. This is something which, if present, needs to be treated to avoid damage to the eyes. If it's not this at least a neurologist will be best suited to figure out what's actually going on.
Hope this helps. Please let us know how things develop. Good luck to you!
John Kenyon, EMT, CCT
Non-invasive cardiology tech, Emergency and Critical Care technician, Critical Incident Stress Mgmt. specialist