I fell and broke a rib last August. The pain is not terribly amusing. After a few days I succumbed and went to A & E and was glad I went. When it is diagnosed you know where you are and they are ready for you if you call in having blood in your mouth (perforated lung - which can happen).
They don't strap broken ribs these days. They do prescribe heavy painkillers - I gave up with them after 3 days as they were making me even more doolally than usual and giving me awful constipation. However, I had them so could take the odd one if things got bad.
You have my every sympathy, but please do go and get it checked out. If you develop a cough it can turn nasty (I did get one) because you can't breathe deeply enough and then pneumonia is a risk.
The other possible complication is trapped air if a lung has been just scraped - I was alarmed (a week or so later) to lie in bed and watch air-bubbles popping up under my skin and rippling along to my breast-bone. The scary bit is that the air could get into the blood system.
In other words - please go and get it checked out!