The most probable cause of pain is spasm in lower back muscles more on right side.. may be due to continuous sitting in same posture while doing work from home.
Next Steps
I will suggest you to start with hot fomentation, analgesic with muscle relaxant tablet twice daily for 5 to 7 days, apply local analgesic ointment over the site of pain..
Health Tips
I would suggest to use a table and chair at home while working with laptop. Take frequent breaks after every one hour for stretching exercises. Once pain reduces, start with back strengthening exercises.. Avoid forward bending, avoid sitting down, avoid heavy work, avoid Indian toilet..