If the SI joint pain is mild and not severe then the SI joint pain should go away and heal up on it's own within 2 days to 14 days.
More severe cases of SI joint pain may last for a month or longer and may need treatment by a doctor to manage the SI joint pain.
When my SI joint pain flares up the SI joint pain is just mild and goes away within 4 days of it starting.
You can take some pain medicine and apply a heating pad to the SI joint pain area to help ease the pain.
After a few weeks the SI joint pain should go away and if not or the SI joint pain gets worse then see a doctor about it.