Am post op recovery - since early January find that when I sit too long my muscles in lower back just below my tailbone the muscles hurt.  My hyster was april 10 2013... maybe weight gain... have to always sit on cushion to be comfortable this last while - am a hyster sister member.
It is a common thing to have pain after hysterectomy or Caesarion section. This is because abdominal muscles are not providing support to back. I would like to suggest back muscle strengthening exercise. Also, you should wear lumbosacral belt, so that abdominal muscles able to support your back. Also, I would like to advice you muscle relaxant like Moral or MySpace. Apart from this apply Diclofenac gel. Hot water fomentation and back strengthening exercises is also helpful you.