Good luck and I hope you get better soon! Definitely seek medical help if it doesn't get better in the next couple of days, so that you aren't having to suffer through the pain. And please keep us posted on your recovery 🙂
You might not have necessarily subluxed a rib–my guess is that you sprained the intercostal muscle (the muscles between the ribs that assist with breathing). Make sure you ice it 20 minutes on and 20 minutes off for the first couple days. And rest it–no inverts or extreme poses for a few days if possible. Then ease into things and make sure you're properly warmed up next time you try those darned inverts 🙂