Dear Doctor, I Have Been Having Some Sensitive Feeling Somewhere

Dear Doctor,
I have been having some sensitive feeling somewhere in the mid section of my spine for a couple of months. Last week I carried a 25 kg load up a flight of stairs without feeling any pain on my back then. However 2 days later I felt a sensation, this time on my lower spine. When walking this sensation once in a while gets pronounce for a split second when a certain movement aggravates it. It is not exactly a pain but something like a feeling of raw nerve.

In the light of the above circumstance would you kind enough to throw some light into what is the reason for this sensation at the 2 areas of the spine?

Thank you.

Sincerely,
Jeffrey L