Do i have to take b12 shots for treating sciatica?

no: Sciatica is caused by nerve impingement in the vertebral column. Most cases resolve with conservative therapy, including physical therapy and and anti-inflammatories. In certain instances, epidural steroids will help and rarely surgery is indicated. B12 is not a typical treatment for sciatica.

Pinched Nerve: Sounds like you have a pinched nerve in your back. I would suggest seeing a pain/spine specialist to evaluate you further to evaluate what level and what can be done to treat you. There are interventional treatments besides medications and surgeries that might reduce or eliminate the pain altogether. Unlikely that B12 shots will help much.