It could be due to spasm in the low back muscles.
How long do you have this pain?
Next Steps
You should give hot water fomentation for 15-20 minutes twice a day for a week.
You can use Volini gel or spray provided you are not allergic.
You should do back and hip stretching and strengthening exercises with proper guidance.
Health Tips
If the pain persists or aggrevates you need to consult a Physiotherapist or Orthopaedist in person or through video call for further evaluation and treatment.