So, OP, let me start by saying I totally appreciate the severity of your situation. We are a Harm Reduction community, so I can't very well close this thread, given the fact that you are apparently causing a slow death for yourself by using Cocaine. If you are losing "crazy weight" and have, by your own admission, pustules in your nose, then the only reasonable suggestion is going to be ceasing your use of Cocaine immediately.
If it is not possible for you to put down the Cocaine, which again, is the only reasonable thing to do at this point, you need to use a different route of administration before you destroy your septum. That's not to say you haven't destroyed it already, as the already existing pustules could very well develop into death of the tissue as bptubbs has accurately noted.
The problem is, we are a Harm Reduction community, meanwhile, the use of Cocaine, in both an acute and chronic sense, is innately harmful. Opioids, for instance, can be used chronically, indefinitely, so long as the person maintains normal function like eating, sleeping etc. Cocaine is inherently cardiotoxic and it immediately exposes the user to severe cravings for more.
To answer your question and I'm not being an asshole, I'm just trying to be objective, is that you are definitely past the phase of "recreational" usage or a "run" as you have said, as you are experiencing pretty clear-cut physical damage to your body and are still continuing to use Cocaine compulsively. So, if we're to get real, you are not likely to be able to use Cocaine responsible or safely in the future. If you can't stop for days at a time, it's nearly impossible for you to somehow return to normal usage.
First off, I think you have to go to a doctor regarding the pustules. I know, maybe you don't want to go and admit your problem, but if you don't go now and seek medical attention, you could progress to a condition that requires invasive surgery. If they think you're a drug addict, which will be pretty apparent when they look in your nose, you're probably going to experience surgery without any post-op narcotics which is not a fun thing.
If you need advice about the routes of administration, hit us up.