In reply to OneLifeOneHeart: I have had a prolapsed disk in my lower back twice now. The first time I let it stop me doing what I wanted, the second I fought to do what I could. I was due to have surgery on Wednesday this week. But you know what, once I got teh painkillers sorted to a managable level I continued climbing. 3 or 4 weeks ago something changed. My back injury is fixed and I cancelled teh surgery last week.
Don't know how, or why the physion couldn't do whatever it was I did climbing.
I also have the same (I think) upper back issue as you. Have done most of my life since an injury. Since climbing regularly it has all but gone. I can't remember when I last had the pain to be honest.
Without getting personal, you have said that you are overweight. Work on bringing the weight down (diet is the single most important factor for doing this) and improving your fitness. Your fitness will improve gradually, your climbing will improve gradually, and as your techinque improves I bet you'll find yourself climbing higher and harder.
Concentrate on getting your footwork in order, and getting your technique right. This should have you using your arms less to start with anyway and the rest will be a natural progression as you get fitter and leaner.
Try not to think about your back pain. I've done it, you think you can't move this way or that way so you don't and that just makes the issue worse. Your body will compensate to allow you to make that movement, but in a different way to normal. This will cause all sorts of imbalances that just get worse. Think about it like having a stone in your shoe for a month. After a week you'll look like you are walking normally, no one would know about the stone. Your body has compensated, you mind has taken teh stone as normal. Remove the stone after a month and you'll still "feel" that it's there, and your body will continue to walk as if there was a stone in your shoe. Again, it might look normal (and by now feel normal) but clearly it isn't.
What I'm saying is you can program work-arounds and imbalances, but that may just create problems elsewhere.
Hopefully our back problem will get better as you get more active and mobilise the joints etc.
Good luck!