I have the exact same symptoms. CANT SIT!!! Nothing but pain in the butt all the way up to back. I have had a PARS defect repaired L5-S1 fused no relief. I have had a tethered cord surgery no relief. I have fasiculations or visual spasms in my butt all the way down to my ankles. Feels like it’s going off like popcorn poping. I had the burning for like 4-5 years. I had the two surgeries in one year. Today Dr wants me to go to neurologist today to see if pain is coming from brain. Don’t know which way to turn anymore. Anybody got any suggestions.