Relapse Without Active Lesions, But Not MS? Why not?

Do you think a relapse can happen without the evidence of active lesions?

I know that they do. I have researched it online in medical articles from many reputable sources. I was told by a Neurologist that I had no new "active" lesions but do have preexisting ones. The Neuro Doc doesn't think that I'm having a relapse instead they blame it on my lumbar spinal nerve compressions and spinal stenosis.

Why is it that when a Patient has multiple autoimmune diseases is the issue not MS and is a result of one or more of the other conditions? Has anyone experienced this?