Hi pressurtepts,
What type of pillows have you tried. Adding that couple of inches of topper could be causing your head and neck to angle down and stretch your neck muscles in a manner your body is not used to. I know you mentioned you have tried different pillows, but have you added loft with those pillow/s.
It took me a while to get my pillow situation under comfortable control. My Pillow Post.
Even after all that, I just updated, hopefully for the last time, to a horsehair pillow, which works wonders for my sleep. I still think the key is in your pillow, from what you describe, it makes the most sense to me. Don’t give up on the pillow thing.
Norm