i think you should just go ahead and apply. get a good reference letter etc. these days the applications are way down and I think you've still got a good chance.
Yes, request a specific letter and a general one. Make sure to specify as much in the requests. Then, when you are choosing which letters to assign to which schools, you'll have the ability to assign the specific one to the school it is tailored to.
I second the yoga recommendation. If you can get to a vinyasa class 1-3x/wk, it could really help your back. I felt awesome when I was consistently doing yoga and taking 3 PTs/wk.
So glad you've all found it helpful! and @stephgmeister yes he did! He started in litigation and has since moved into Mediation building on that experience and loves it for all the reasons the letter lays out :)