Scarring of the incision is not the same as scarring of the nerve roots in the lumbar spine. A severe and even a tender or painful scar on the skin does not reflect on scarring in the spinal canal.
The “tail bone” has many connotations to patients. Some individuals correctly point to their coccyx (right in the middle of the gluteal cleft) and others mistakenly point to their sacrum or even sacroiliac joints as the “tailbone”.
If this is true coccyx pain, there are many causes including injury to the coccyx joints, referal pain from a nerve root or even an inflammatory syndrome called pudendal neuropathy.
The first stop for a consultation could be a PM&R doc, a pain doctor, a spine surgeon or a neurologist who specializes in this area.