In my two years of increasing dosages of painkillers, the pain did not go away, in fact it got worse, and the painkillers did nothing for it. If you are on such heavy doses and it's not working, then it doesn't work....and yes, you are destroying your liver, big time.
For me personally, my pain was from bracing. Notice how your body feels just prior to an attack, or even during an attack. Pay special attention to your shoulders in between attacks. Are they up around your ears from anxietY? If so, you could have a traditional case based on pulling your chest out of alignment. Relaxation is key here. You need to stay hyper aware of your shoulders and stress in your upper body if you feel this is the case.
A really good massage therapist working on these muscles did wonders for me.
In between, get a very good guided meditation tape (the whole Naparstek series are amazing) which you can get on Amazon.
Bathing in Epsom Salts may help to due to the magnesium.
Even if you have a classic case of chronic costochondritis, you can lick this. It takes not eating crappy food, too many stimulants (like coffee), tons of water, and the relaxation techniques.
I did try accupuncture at one point, and it didn't help me, but it might help you as well.
Good luck. If you've been on pain killers for a couple of weeks, and it doesn't help, it won't. Believe me.