I have had the spinal nerve blocks as well and it can be quite painful.
I can only state my experience with both surgeries and sedation...it takes twice as long as someone who does not have FMS/CFS to recover. I do not do well with any form of anesthesia or pain medication and it takes forever to wear off (and typically doesn't do much for the pain in the long run). I also know that some experience a spinal headache from this procedure (worse than a migraine). Sedation, itself, tends to make me feel blue and tearful. It should wear off in a few days. If not, please contact your doctor or his nurse to discuss your symptoms.
Take care.
I have not felt right since my heart ablation last March. It was a verrrry stressful procedure that I was awake for and was strapped to the tabel for 6 hours. I also could feel when they ablated which the doctor said has never herd of before. The whole thing was horrible and I really belive the stress of everything triggered this. Just my opinion.