It actually feels more like a rib. The top most rib. I've broken my collarbone 3 times. The same side. It's now the thing I think about most. Every waking moment is a strategy in how to avoid any sudden shock or strain to the shoulder.
Aside from that, it's not that the bone hasn't healed. It's certainly healed by now (I haven't really hurt it to the point where I bleed beneath my skin again in over 4 years). But whatever muscles and tendons that form around it (the healed/fused bone) rest on a rougher surface than a smooth, unbroken collarbone. At least that's what it feels like. Every breath. Every day.
A distraction like no other
After feeling pain level 10 (what you imagine as pain level 10) right when it breaks, then a steady stream of pain levels 3-6 depending on things like ambient temperature and shoulder activity, pain relief and pain avoidance became the priority. If the weather suddenly becomes colder, it hurts more. Probably because of muscles constricting and blood thickening. If I pull or twist with more than 50lbs or so, it hurts more.
That doesn't mean I can't lift, pull, or twist more than 50lbs. But it feels like the bones are being pulled apart again. But what's really happening is probably just some nerve, muscle, and tendon inflammation around the bone.
Interestingly, there is a little less pain when I put pressure directly on the muscle below the old break. I can achieve this by placing a folded pillow in a headlock. It also helps to take some of the arm's weight off the shoulder by redistributing it to the elbow on a surface like a table (usually padded with a book or mouse pads). Holding my breath with lungs fully inflated seems to help (probably because it puts pressure on the same area as the pillow, only from the inside).
This is current state after all the physical therapy that the insurance would pay for (three times, once after each break). When it gets really bad, a topical seems to relieve the pain the best. I'm using diclofenac sodium gel 1% only when it hurts greater than pain level 6. It helps. My old doctor (an orthopedist) prescribed naproxen. This was a horrible choice. The diclofenac sodium gel prescribed by my new primary care doctor works much better.