Muscle spasm usually get relived with physio and muscle relaxants. If it is still persistent you need to take rest and do physiotherapy as your strain is still persisting on the back.
First relieve stress on back , maintain proper posture , sleep on hard and straight surface.
Continue you medication along with topical aceclo gel and hot pack with physiotherapy including interferential therapy or ultrasound therapy.
Next Steps
Rest , hot pack , continue physiotherapy