Re: swim without arching back?
I am sorry but I can't remember your story? drugs, you know.
I will tell you that swiming is something that most dr's to not recommend for awhile. Have you done walking in water? I know it sounds lame but it is very good for you, much better than regular walking.
As far as not arching your back I would try noodles ( those long floating things) place on under your hips and one under your chest while floating on your stomach it will take some practice to balance but the flotation from the noodles will keep you aligned. Please be careful though swimming is very hard on your back ( if you are doing freestyle correctly, lots of twisting that is not good for people like us) Take it slow, it will be something that you will have to learn, once you can feel how your body needs to be held you can remove the noodles. They are sorta training noodles !