Hi @Swoo,
It sounds like your IJ compression may be causing changes in your intracranial pressure, typically high. This fits with the positional symptoms you have mentioned. Intracranial HYPERtension is usually accompanied by a headache on the top of your head, eye pressure and ear pressure when lying down. Intracranial HYPOtension would be paid at the back/base of your head and typically improves with lying down. It would be prudent to have someone evaluate you for papilledema if you have significant eye pain or vision changes with looking down ets.
Here is a link to research hot off the press. To access the full article click on the “full text links” box at the upper right hand corner of the page. The surgeons are from the Barrow Neuro Inst out of Phoenix, don’t think they are listed on this site but clearly they have been treating IJV ES and IIH for a while now. Hope this is helpful!