What Causes Pain In The Lower Back And Abdominal Bloating Post Hysterectomy?

I had a hysterectomy in June 2014, they left the right ovary only. For about a month I have been bloated and my stomach is tender to touch, along with a dull constant ache in my lower back on the right side. The lower back ache seems to be worse at night. The bloating seems to be worse in the day time. Any advice?