Sounds very much like Costochondritis a common ailment in Fibro. So get it check by doctor for confirmation
I live with it constantly just a varying degree of pain level so here's a few tips in dealing with it.
Anti inflammatory gels are best for rubbing directly onto ribcage front and back. If you can't or don't want to use ibrufen based products ( I don't by choice) use a deep heat rub alternating with a Biofreeze type product.

I make my own warming rub with Vicks menthol vapour rub and add lavender and frankincense essential oils.

Also alternate between heat blankets/pads and ice packs- I use a large bag of frozen peas as it's easily shaped around ribcage

Rest is important and I find lying propped up on pillows more comfortable than lying flat or sitting upright

Try having Epsoms salts baths at night before bedtime to help you relax to help sleeping pattern

Hope some of this helps, gentle hugs and God bless xx

Welcome to the world of fibro; costochondritis plays a big part of fibro; I have had this terrible pain in my ribcage and breast bone for over 35 years. A bad flare up can leave me in agony and very hard to take a deep breath; it is with me always and I only ever wear a bra ( as this gives me pain ) if I go out which is not very often. I am sorry that you also have this condition but there is really no cure. Putting a freeze gel on the area can help somewhat x

Thanks everyone, I'm going to the doctor in the morning, hugs to all

Infrared sauna helped me with pain. Has to be low temp full spectrum.

Yes you have costocondritis; his plays a BIG part in fibre; I have had it for about 35 years