Sore mid-back muscles on left side

Hi,

I had a cycling accident in a triathlon on July 18.  Thankfully, I wasn't seriously hurt, and most of my injuries are healing well (road rash and broken wrists).

However, when I crashed I landed on my back, and since the crash I have had deep pain in the muscles on the left side of my back (see picture below for location).  The muscles seem to be healing very slowly, and they get worse when I run.  They hurt when I engage them (especially when I get up from the floor/bed), and they hurt when I push on them.

Anyone have any suggestions for speeding the healing of these muscles?  Would some kind of massage therapy be worth trying?  Something else?

p.s. Had x-rays taken of my back after the crash and they were negative.