It happened for the first time around February last year, I had someone check my back but there was no signs of anything. It lasted for a few months, 2-3 and disappeared. This strange feeling has just came back, exactly the same spot, just under my right shoulder plate. It's about the size of a fingertip, and the "pressure" comes and goes, and when it's there will vary depending on my position, sometime very light, but other times it can be anoying, not painful, but disturbing enough to make me stop what I'm doing.
Few pointers about me, I have a very strong immune system, thick skin (so said my tattoo artist), thick blood (I usually don't bleed from a small to medium cut) and am a lot less sensitive to pain than most.