Anon
In light of your various medical problems, your back and leg pain is most likley multifactorial in its etiology. As such, there may be no simple or single way to address the pain issues. It is unfortunate that your surgery did not provide improvement in your leg pain (sciatica). No pain surgery is guaranteed, even one as successful as spinal stenosis surgery. I assume that you have discussed the possible causes of failure with your surgeon and have determined that there is no simple solution. If not, I suggest you do discuss why your surgery "failed". It may be helpful to get a second opinion from a another surgeon to determine if the orginial problem was adequately addressed or to ensure that a "new" problem has not arisen. Having said the above, the general rule is that subsequent surgeries are less likely to be effective than original surgeries. This is particularly true in patients with a generalized pain disorder like Fibromyalgia. It would be prudent to be cautious with respect to further surgery.
With respect to your Fibromyalgia, this is not a surgically treatable problem so it is not surprising that these symptoms did not improve with spinal stenosis surgery. This is a systemic pain problem that is thought to be due to "over sensitive" pain nerve endings. The treatment is usually medical and multimodal often best administered in a comprehensive pain clinic.