MS Contin (also available generically) is continuous release morphine sulphate, which is metabolized in the liver. As I think you observed, there's really no way to tell how you (or anyone) will do on any pain medication without trying it, and carefully titrating to establish an effective dose with tolerable side effects. That could take some time, but that's just the way those things go.
It's possible to find/have a pain management doctor with a background in neurology, but there's nothing that should preclude you from having more than one doctor on your
team. Again, it can take some time and considerable effort to build a team that's the right fit, but many of us can tell you it is soooo worth it.
I think most of us have multiple doctors, but that's a personal choice of whether you prefer multiple perspectives or are more comfortable with one doctor managing all (a role usually filled by the PCP). There are no right/wrong answers there, but in this day of specialization, the latter may be a challenge to find, especially in a limited plan pool.
Many of us know, and can relate to, the "guinea pig complex" well, and the unpredictable, unreliable life of one day at a time.
Doc