Re: cavity or filling misery, poss exacerbated by oil pulling - and can't afford a dentist :(

I'd continue to oil pull with the oil/oregano oil mixture. It won't hurt to add some oregano oil directly to the abscess. I'd try swishing with salt water to draw out some of the infection. I'd do the saltwater swish prior to the oil pull.

Besides the things that i've mentioned, the only other options would be a root canal or extraction, which i'd leave as a last resort.