I'm sorry to hear about this, I hope that you weren't injected with a steroid contaminated with fungal meningitis, which you can read about on my website.
The only way to know if there was malpractice is to retain a med mal lawyer who can order the medical records and send to an expert to review to ascertain whether there was a breach of the standard of care.
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Asking whether a doctor is "allowed" to do a procedure is the wrong question. The question is whether it was an approach that a reasonable doctor might take, based on the circumstances. Since diagnostic injection is generally low risk, I suspect the answer might be that it was within the standard of care. But that question requires evaluation by an expert physician. The next question is whether your injuries are sufficient to justify pursuing an expert evaluation - which I cannot tell from your post.
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