I think RustPot may be on to something here. With my second daughter, I remember my back and shoulders aching a lot because she was a baby that needed to be carried around a lot if I wanted to retain my sanity. I also had an 11 month old at that time too and she also wanted to be picked up a lot. What I found helped me a lot was to hand the babies over the the husband, take some Motrin (or Tylenol) and take a long soak in the tub with the door closed and the music turned up!