OK ALREADY HEATHER, we get it!!!.......

J/K, you know me.
First of all, unless ya are prepared in all ways to be breeding any bird, you should have them in separate cages.
I would put a nest in there asap and nesting material (white sisal string is best). Like Heather said, extra calcium and egg food and some greens (fresh crispy well washed very green, patted dry Romaine lettuce). Ya might want to add some fresh, raw, well washed brocolli also. I give mine a wedge of fresh orange and apple without seeds occassionally.
Ya should always have a ceramic heat emitter hooked up or at least available and ready to go for needed warmth for any bird. Ya need to also have proper humidity around too. Make sure ya got a cuttlebone in there and give well boiled eggshells also and a touch of calcium/oyster shell grit once in awhile.....ASAP, invest in proper Full Spectrum Lighting too. Cage should be a good size (IMO, minimum 3x3x2 ft high), bigger would even be better. Have a water bowl in there (somewhat shallow for bathing and wetting brooding feathers)......
Any signs of swollen vent area? Did ya feel the chestbone/keelbone to see if sharp and protruding? Can ya weigh her on a gram scale without stressing her too much? Is she breathing heavily or tucking head in feathers often? Is she perching properly?
Sometimes it just LOOKS like they are eating more when sick but in actuality are not eating, just mouthing the seeds. Make sure the seeds are being hulled by checking them closely on the cage paper at the bottom. IMO the cage should have a wire grating unless you are super clean and always picking up after them but even then I prefer to use a grating on the bottom and keep that as clean as possible too. Cut back on the egg-food for now. A well experienced Avian Vet (take preferably to one who has kept birds his/herself at one time or another) visit is of course the best course of action to be safe. Always best to also line up/find a local canary breeder and try to befriend that person and learn all ya can for future problems that may arise. Join a canary forum also and purchase some books on canaries & on breeding asap.