Did the pain start by itself or did she have any injury. Does the pain get worse with mobility or improve with rest? It could be either nerve compression or a hairline fracture. Patient needs to be seen by a Spinal Surgeon or Orthopaedic Surgeon for correct assessment. May need x-rays and scans to make a definite diagnosis.

Avoid all exercises just now tk physiotherapy treatment  after relief do spine stretching and leg stretching exercises. Sciatica pain  is there according your age x-ray  MRI must.

Apply Hot Fomentation twice daily. Avoid bending in front. Postural Correction- Sit Tall, Walk Tall. Extension Exercises x 15 times x twice daily - lying on tummy, take left arm up for 3 seconds, then bring it down, right arm up for 3 seconds, bring down. Bring right leg up, hold for 3 seconds, bring it down. Then right leg up and hold for 3 seconds and bring it down. Repeat twice a day- 10 times. Bhujang Asana -- Lie flat on your stomach, keeping the palms out, bend the neck backward, take a deep breath and while holding it for 6 seconds, raise the chest up. Release breath and relax your body. Repeat the exercise 15 times twice daily.

Dear Mam' Was there a history of any trauma like fall or jerk? Was it a sudden onset?? Kindly provide more details.

This could lumbar Radicular Pain

Start with back pain relieving exercises. Sending you the link of the same https://play.google.com/store/apps/details?id=com.backpainrelieving.backpain