SI joint pain is some times due to malalignment of bones and sometimes due to poor mobility of lumbar spine{lower back}.
Manual therapy is best treatment available for this issue.
Spinal mobility exercises and Gluteal muscle strengthening along will core stability exercises will prevent the recurrence of SI joint pain
Next Steps
Visit a nearby physiotherapy clinic,
take few session of manual therapy
Health Tips
Avoid standing on one leg when you have to stand for long time.