Dear Bhissett

From your posts, one can tell that this current problem worries you. I would agree with physiobob on his suggestions. While there might be no connection, I could not help but notice you had a fracture previously.
Is there anyone in your family with this problem? (the current one i mean-sinking right eye). Have you had issues with the sinus in the past?
Unfortunately, this field is beyond the scope of physiotherapy, however like physiobob has suggested undestanding the state of your bones generally might give a better insight as to why this has happened...

The good thing is, from your description, it does not seem to be getting worse...it feels like a gradual change in skull pressure with weakned bones made this happen...
Did you have a bad case of an infection during that period-2007? You did say you are a healthy female, during that period when you first notice this issue, did you have sinus issues...

It is good to rule out a neurologic disposition however i doubt if this is the case with you...

I feel that some surgical intervention may be the answer...however it is good to have the understanding of your bones first of all...i presume this would have been picked up in your previous radiographs if this was an issue...