MRI increased signal in white matter

Can someone help?  

Right side of face pain has increased, is more severe and more frequent, have another sinus infection on left side, still having neck and back pain.  Still very, very tired.  Having tingling in right thumb and index finger.  Brain MRI shows significant increased signal in white matter in brain stem on left side and it is not diffuse.  Does any one know what this means?  I have an appointment with a neurologist on 8/6.  My GP says it is not life threatening, is not a brain tumor, not cancer, not ms. He said it could be decreased (or increased) blood flow ???  From what I've read it could be aging, dementia, or nothing...???   He put me on migraine medicine and antibiotic, also on B-2 and magnesium oxide and nasonex.  Also talking about an antidepressant.  Also been told to get hysterectomy and bladder fixed, am falling apart.

[JEANNE545]

I forgot to add that now I have a bad taste in my mouth when I drink liquids.