Thought I would provide a follow-up to this thread.
Went to the Doc today and explained out my symptons. While she agreed they could be signs of a compressed disc she has diagnosed it as nerve pressure damage in the hands from leaning on the bars heavily on that trip - similar to the images attached in this thread of pushbike riders.
Further supporting that I was riding the GTR the other day and consiously thought about my hand position on the handlebars.
I found that when I am cornering quick and using the brake, my index and/or middle finger covers the brake twisting my hand sightly inwards putting pressure on the area between thumb and index finger - this is likely the cause of the weakness in my right hand from nerve pressure damage.
Because of how I use my right hand in fast cornering/hard braking, my left hand takes slightly more weight and it twists outwards putting pressure along the outside edge of my hand - this is the likely cause of the tingling/numbness in my ring and little fingers from nerve pressure damage, and the fatigue pain I experience in my left shoulder.
The doc says that nerve damage will re-generate at a rate of 1mm per day (and take Sundays off

) and says it could be like this for quite a few weeks more. She is, however, confident I haven't done any permenant damage due to the strength in my right hand has mostly returned, and the tingling/numbness in my left has been slowly getting better.
I've ordered a set of risers and wedges from Murphs, as well as a new Cee Baily's screen so I'll see what they do for me.