It could be scar tissue that is causing the pain.
It could be a kidney infection. Please google kidney infection or even bladder infection and see if the description matches it. Something about it being on the right side rings a bell for me about kidney infections sometimes being confused with appendicitis because of that.
From what I understand, the uterus is all that's removed, so you should still have ovaries. As such, you could potentially have a cyst since you're still forming estrogen and such. A website I looked at said that those close to menopause should be warned of the risks involved with leaving the ovaries in place, one of which is indeed a cyst.