If your ischial tuberosities are sore and numb with local - then why have you not had steroid injections? If widespread, I have had to do more than one. Information on prolotherapy for Ischial bursitis is scant and best mixed with Platelet rich plasma (PRP) injections Subsequent any hamstring and inferior Cluneal nerve issues will need addressing. One spinal block? In past, 3 blocks were needed to fully decide on spinal block effectiveness - I call this use, a "One -Shot Wonder" - going through motions but not fully trying it out.
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Both sides sore? - might need a cushion used by paraplegic wheelchair sitters.