Aka PAINFUL inflammation of the cartilage between/under your ribcage. Mine feels like a really deep bruise and occasionally wakes me up with sharp stabs on the L side. No R side pain, and I've had my gallbladder and appendix out so I know it's not referred pain from one of those issues. Saw my midwife in the ER and she said it was more than likely just costochondritis and I should rest and ice it if it got more severe. Anyone else have this and have some advice on what worked for you?