Several times a year, trigger unknown, intercostal muscles ache like crazy, and it can intensify where it feels like it goes through the bones. But, then it's gone....weeks, then gone. Yeah fibromyalgia

It's very random but it can last from a few days to a few weeks or months. It's very different person to person.
Hope you find relief soon

I've not been diagnosed with costochronditis (?) but if I forget and scratch an itch on my ribcage, it is agonising.. can't bear many bras or anything tight around my ribs - probably not helpful to your question, but unfortunately this is all the time... xx

Mine seems to last forever, I've had it for months and it doesn't seem to let up. Am having invesigations to see if it's something else or if it is Costochondritus. Because when you see a doctor they always lump everything in with your fibromyalgia don't they. Sending you gentle hugs 🫂

The first time I experienced this I thought I was having a heart attack. Went to ER, found nothing, and was sent home with antacids. 🤣 I still get it from time to time. Usually lasts a couple of days for me. Really don't know what to do to make it feel better.