Something is wrong. Pain between my shoulder blades.

[Dry Bones]

Just saw this post.. Dang It. Hope you got your back worked out. Never had any military experience but lots of miles chasing bucking horses. We used Naproxen (Alieve), and a stubborn mind to get through the "bite" that occasionally happened.
I have really tormented my right shoulder and my movement off of it is somewhat unique to say the least.
This is not good form, or anything to really suggest, but just another thought.
I draw straight off my arms, no back into it. When I try to really put it in my back my shoulder cries to much so I have learned to draw through my chest and arms. Again this is not a good idea for accuracy or long term but it works for me. I have been able to shoot much heavier bows then I should, just due to work out and will power. I know a man that has a 90 lb longbow and 85 lb recurve, I have successfully shot both the same way. It can work but I developed this because of my limited shoulder rotation.
Sometimes our bodies mechanics do not follow the same medical chart diagrams and we need to modify how we go about things in order to make it work.
Do not be afraid to experiment, and also really think about the draw cycle and where you anchor. This can change the angle and tension of the muscles you use.
Good luck to you.

[Draco]

I would bet that your problem is because of improper alignment. Remember, the most important part of form when shooting trad bows is the line across your body, shoulder to shoulder, should be in alignment with the target. If it creeps in so that the line is pointing more to the left (if you're right handed) then the strain on your shoulders and back go up drastically. Your bow arm shoulder should be low and your bow arm should be bent downward.

Try to find pictures of Howard Hill and copy his form exactly. He stayed shooting very heavy bows until very old. This is not to say you can't shoot well with out doing this, it is to say you will have health problems with your shooting if you don't.