Jeff007,

Have you tried sleeping in a recliner?

You can maintain better head and neck position in a more upright position.

My concern is you have inflammation that is changing blood flow to your head. That can be posture/position related.

If you can get checked by a Physiatrist (Physical Medicine and Rehabilitation), they often have better understandings.

You did not trigger a ten year old concussion. This is a new issue. You may just have less tolerance after that concussion.