Good that your DH has been referred to Neurologist. Assuming you are in England there is quite a wait for Neurology appts, in my area South Coast.
I have RRMS, my dx was private, this was my journey - I noticed an area of numbness, across my ribs which grew greater each day, numb hands, pins & needles, walking sensation altered, felt this walking on marshmallow.
Saw GP, performed basic neurological exam, told me to see Neurologist urgently, saw Neurologist, arranged MRI scans, blood tests, chest X Ray etc. Had MRI, three areas Head, Cervical & whole spine, lesions were found on my brain and two areas of inflammation in my spinal cord. I was dx with Transverse Myelitis, but was told that it was more than likely MS, this was confirmed, two years later when I had further relapse. Symptoms were visual this time.
My advice would be to go private if you can afford it, it will be much, much quicker. In my experience when a Neurologist suspects a possibility of MS, they rule out lots of other conditions that can cause similar symptoms.
I know it’s an extremely worrying time, but try to think positive, chances are it won’t be MS, but even if it is there are effective treatments for most types of MS. Wishing you all the very best for the future.