It looks like acute lumbago without sciatica.
Bed rest compulsory for 3 days with medicines to be taken. Can take physio sessions of SWD or IFT to relieve pain along with mild stretching exercises.
Next Steps
Visit an orthopaedic or a Physiotherapist, get yourself checked up properly. If pain doesn't subsides in next 3 days, go for an X-RAY or an MRI
Health Tips
Hot water packs for 15-20 mins twice daily. do movement which are required.