I did similar last year. Saw the doctor. He said that if nothing was sticking in or out, thenit ddidn’t matter if it was broken, crack, bruised or pulled intercostal muscle, the only cure was time. I was told that several times a day I should take ten deep breaths to fill the lungs, fully exchange the air to avoid any infection as the tendancy is to shallow breath.
My mate’s however, did all they could to try and make me laugh. I saw the doctor because after a couple of days, the pain got worse. Apparently, this is quite normal as the muscles tense up to hold it all still, as they start to relax, it moves more and hurts more.