I’m unclear how you tore your intergluteal cleft from the coccyx and how that diagnosis was made without imaging. You then note “When it tore I was unable to walk effecting both legs”. Was walking painful? If so, where was the pain? If it was weakness, what muscles were weak?
You note “I have lost function of the lower sacral nerves”. I am unclear why that would be as these nerves serve sensory to the rectal area and nerve loss would affect bowel and bladder function.
You then note “if I even touch belly button the pain radiates to my back, down my thighs, pelvis and up to my chest”. The belly button is supplied by the T10 nerves and below so you could have lower thoracic problems as an origin of your symptoms.
You certainly need to start with a lumber spine MRI that covers the lower thoracic spine to at least T8-9 based upon your symptoms. A pelvis MRI might be necessary but I would hold off until the lumbar MRI is performed. A pelvis MRI would cover what your complaints are but remind the technician that the posterior buttocks region and sacrum need to have close attention.