Thanks for your query.
I will try my best to provide you with best possible professional recommendations to your questions.
I think the pain might due to sprain
. Extra cartilage
is unlikely, you can confirm it by getting an x ray chest and with x ray even any hair line fracture
if present can be diagnosed.
For pain use any of the over the counter pain killers and even you can take muscle relaxant
Yet again, I do hope that you have found something helpful and I will be glad to answer any further query.