I had my total hysterectomy (and ovaries) removed in 2004; was fine until about 2011 and now I'm registered disabled. The new consultant is of the view that some ovarian tissue may have been left and along with the endo being able to regenerate itself, assuming some is left, then this can cause problems. Hysterectomy is not a cure and it is only the last couple of years that this is being acknowledged even by specialists. It can help some - as with other treatments - but others may find that their symptoms continue. I'm on Prostap SR again (had it before about 20 years ago) and it seems to have reduced the severity and frequency of pain but not the pain in its entirety if that makes sense.
If you take painkillers regularly, you may also find that these mask the severity of pain you're feeling; it is one of the reasons that painkillers should be taken only with the onset of pain - although we've all done it where we feel a niggle (or to avoid the niggles coming) to avoid it getting worse, we down drugs. I now try to take the painkillers only when I'm actually in pain but sometimes that doesn't work either.
It's sad that this disease just seems to be never-ending; a few years respite was all I had although I don't regret it and would do it again.