Resolved questions
What's the feeling of "dull, throbbing numbness"?

As I looked out onto the trees that edged the road, my muscles tensed and I began to sweat. I knew where I was: a road in Germany, AWOL, waiting for the flight back to the States. But my body did not: a road, the edge of it, and another day. My fingers closed around a rifle that was not there. I told them the rifle was not supposed to be there, but my fingers would not listen, and they kept closing around the space where my rifle was supposed to be and I continued to sweat and my heart was beating much faster than I thought reasonable.
I was supposed to be happy, but I cannot recall feeling much of anything except a dull, throbbing numbness.
What's the feeling of "dull, throbbing numbness" in the last sentence?
Thanks!