Mid Back Pain

Male. 32 years of age.
Three weeks ago, after running (just over 4 miles) the right side of my mid back, just below the left edge of my shoulderblade, began to hurt badly. It’s a type of sharp ache that I can only describe as like a blasting headache in my back.
It’s now been over three weeks and the pain has not disapated in any way. Lying down or sitting in the right position alievates the pain completely.
It’s as if nothing is wrong.
However, when I stand or walk the pain starts almost immediatly and then within minutes reaches its peek.
It’s not the kind of pain that hinders movement or that makes me double over. Rather, like I mentioned before, it’s like a bad headache in my back.
I’ve now been to a chiropractor, 2 doctors, gone for massage (shiatsu) and physiotherapy with no results. X-rays were looked at by the chiropractor and nothing was founds.
I don’t know how to explain it any better than this. Agian it hasn’t gotten any better or worse in over 3 weeks now.
The only difference has been my tolerance to cope with it. Any help would be appreciated.
Thanks.