If your mother has such severe pain ,it could be due to bulged disc in low back.There are other causes too .Pain could be disabling.Since you have not provided any other information, could not comment much.
Next Steps
You could consult with orthopaedic surgeon or neurosurgeon who deals with spine ailments.Perhaps she may need strong analgesics, physiotherapy and MRI
Health Tips
if she has no asthma ,
kidney ailment ,you could give her Voveran plus three times day for few days along with neurobion 1 daily till you arrange for a appointment with doctor