It sounds as though this latest tooth is extremely infected if it is black/brown and damaged. I don't understand what the bonding is that you mentioned. I assume you have had X-rays etc and your dentist is certain what is going on with your teeth before he recommended a root canal on what sounds like a badly decayed tooth?

You need to do some research and question whether a root canal is the right course of treatment. It might be better to consult with an oral surgeon than a dentist especially since you are having ongoing problems. A root canal treatment isn't carried out because there is a problem with the nerve in the tooth. It is carried out to kill/remove the nerve in the tooth so that you don't actually feel the pain or sensitivity that would otherwise be there. The root canal treatment doesn't fix any underlying oral problem such as infection, gum disease or other weakening of teeth. That would require the underlying issue to be identified and some other treatment carried out. Some dentists will automatically do a root canal first because they (and/or the patient) want to try to save the tooth. This is understandable but may well not be a healthy course of action. Some will do it because they know they get paid for the root canal and then also for the inevitable follow up work leading to removal.

If this tooth is badly infected then a root canal will actually retain at least a residual pool of that infection in your tooth and possibly also in your jawbone. It could be that the course of problems you have been having with your teeth recently are a result of a systemic oral infection which you can't physically see but which is present in the jaw bones which your teeth are anchored into. If that is the case, you need to have that issue identified and addressed as a priority or it will likely cause you even more problems with teeth that seem healthy just now.

One of the key culprits for oral problems is medication. There are many drugs used for CRPS which are well known to cause terrible oral side effects. Even just drugs which cause a dry mouth can have a devastating effect on teeth which are not designed to be in a dry environment. Have you discussed your medication with your dentist to rule this out as a potential cause of your problems?

I am sorry if this isn't what you wanted to hear but I think its important that you don't just patch up a problem without researching the issues and perhaps taking more specialist advice from an oral surgeon given that you have been having other problems which don't seem to be going away.