welcome to Health care magic.
1.You don't have to be on any medication or underlying medical conditions to have disc space narrowing.
2.They are degenerative changes which occur by age related, body weight , heavy work related, sitting position, excessive usage of joints,trauma.
3.The numb ness id felt because of the
disc disease which causing narrowing, the disc might be compressing the
nerve posteriorly, or chord.
4.Get an
MRI done it will give you the exact picture of the nerve / chord condition.
5.You will not feel any thing like temperature or
cold of this reason.( disc disease)
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.