I think I may have this. I've been experiencing discomfort on my left side for over a year.
It started with a weird internal itchy sensation deep in my side by my ribcage. Over time it's now become very tender, sore and clicky when I rub the side of my ribs. I also get a clicking sensation when I press the small of my waist!!
This all started after changing my mattress which I found a bit too firm. I have back issues and for the last 8 years have only laid on my left side to sleep. 80 % of the time when I wake up my side aches and is so sore and tender. I'm sure this is a factor in all this and I wonder if I've damaged my floating lower ribs by constantly lying on my left side every night.
I've also experienced some gastric issues...acid reflux, burping, a sloshing sensation in my stomach! This can be linked to the floating rib issues. Anyone had similar?