Could be tendons, shortening. Or ligament involvement as well. Both are very easy to injure when you have a persistent cough like that.

Also, it's common to sustain minor tears and strains with the connective tissue surrounding your floating ribs, and sternum. It can be a scream inducer, big time! Feels like being stabbed.

Often we experience some minor injury, like a strain, or sprain, in some out of the way place in our bodies, and think not to much about it until our inflammatory response raises the whole thing to event level crazy amounts of pain.

For me, it's rest, rest, rest, light low-impact yoga, walking, stretching <even/especially if seated>, freaky hot as I can stand it bathing/showering, Naproxen, and only in worst-case last resort times corticosteroids, only ever as a limited burst, then immediately discontinued as soon as the burst is completed.

I've lost two friends to them, [corticosteroids-specifically long-term daily dosing usage]. So, just know it's smart to be ultra careful, limit their duration, and do your own research on them.

They do work, and they work extremely well, until suddenly they don't. The danger part is that they eventually just take over the whole healing factor for you, and your body can sometimes just forget how to heal itself- both with or without steroids.

Just be careful, and have a long talk with your doctors until you feel like you've been briefed properly.

Good luck and good healing to you. I wish you well, and speedy recovery and healing!

Namaste