I've lost females from spawning before. One of the issues is if the same female spawns day after day. I think maybe part of the problem is they get too exhausted to actually lay eggs so it goes on and on.
If you feel comfortable you can certainly move the fish to a tank. Slowly raise the water temp to around 75F and the fish's immune system will improve greatly (assuming your pond temp is 65F or below). All the standard stuff, add an air pump, cover the tank with a net, monitor ammonia and do water changes as needed. I would not add salt. If you have a UV filter you can hook that up to the tank and run water thru it slow enough to be a sterilizer rather than just a clarifier. That should kill all bacteria and hopefully reduce chances of infection from the scraps.
If you're concerned she still has eggs... When she's doing better you can add a male to the tank with a spawn mop She can probably handle one male better than a bunch. If they're going to spawn it should be pretty quick. Then you can move the male back. You would want to try and match water temps for this, or leave the male in the tank if the female looks OK.
In the future if you provide a lot of cover in the pond, like a bunch of spawning mops, it will give females a place to hide from males to rest. You may have noticed females will often dart to a corner or bottom to try and get some rest.