If I understand correctly...you now have no outlet on your rear end and you have an ostomy stoma higher up which is quite separate from the problem area. And you still have some lower colon which is producing mucus but has no outlet . So there is no way to use an enema on this situation to clear out the mucus. And I take it that the doctor is unwilling to give you any help. I wish I could it's hard to believe but it ain't.

Except for offering you my best wishes, which does nothing to solve your problem, I don't have any useful ideas. If you are in the USA you could have access to another doctor. Or you could go to the Emerg and they might help you. I'm so sorry, kenc