Your symptoms are pretty typical and are likely not going to change. Much of this, like the chronic sinus issues, is related to radiation. I have had the same symptoms for years and there is nothing to be done in my mind except learn to live with it.

I do not believe in chiropractic medicine, but I have never heard of one that didn't find something like a subluxation between two joints in everyone that they look at, after all its what they are trained to believe causes everything. I'm sure he thought it was something a multiple ($) visits would resolve.

If you have a tooth bothering you that is covered by a crown, there is no way to tell from an x-ray that there is not recurrent decay under it causing problems. You can't x-ray through a gold or porcelain fused to gold grown. All it takes is a crown with a bad margin to leak over the years and you have a problem. The marginal integrity of that crown cannot be determined through radiographs since the angulation of the tube head will either reveal it or hide it.