Simple musculoskeletal strain and posture problem, which means exercise, massage, chiropractor, physical therapy
, palates, etc. will help. Getting into shape in other words, any way you choose to do it.
Lower back, sacral structural problem such as a ligament, disc, or nerve problem. This should be somewhat apparent on examination, preferably from a physiatrist [PM&R specialist...physical medicine and rehabilitation], and an MRI of the area would show all that is needed to see.
Injury to the tail bone during pregnancy, even a fracture. Again, even though an x ray would show some things, an MRI of the area would be the best.
Let me know if you have more questions about this
Please click ACCEPT to give answer credit so that I receive credit. Ask more if needed. Bonuses and positive feedback most helpful. Answers for informational purposes only.