Steff, I agree to look into her teeth and upper digestive tract. Also, can you make her a mash and see if she'll eat it? A few alfie cubes or pellets in warm water, soaked just until soft, still warm, fed right away. With horses we try a little applesauce or something on top to entice her to eat it but I'm not sure that's ok for goats. ???
Hmmm... I went back and re-read your original post here...
Well crud, there was some stuff I read and heard at a recent CALF management presentation about how a COW will have trouble gaining weight through pregnancy, etc. if she doesn't go in in tip-top shape, etc. I can't recall all the limitations but I wouldn't cull her until you get her through kidding and see if she improves or if you can't resolve that hardware issue concern.
Have you taken her temperature lately? I'd advise doing that for a few days and keeping records of it to see if it moves much in correlation with meals, weather, etc. The comment about possible hardware disease bothers me though... Is the vet just afraid to xray a pregnant doe to confirm?? No xray available? Something else??
Have you tried to treat the bloat any other way besides administering oil?
Why were you concerned about too much protein? Was it because of the soybean meal & Calf Manna she WILL eat? Something else?
Can you get a different kind of hay or the same kind from a different source? Look for one that might be more palatable to her??
This doesn't help you much for a goat but incidentally, I had a cat go off his food suddenly. This cat never missed a meal in his life prior to this. There are many reasons an animal can go off their food and even appear to be "anorexic" but for him, it turned out to be a weird infection (likely related to a nasal polyp that won't stay away and is a direct entry portal for bacteria, etc. because of it's location). His kidneys started to shut down and he was severely dehydrated. We administered SQ fluids and forcefed him for a week, adding a big-boy antibiotic at the vet's instructions. He improved greatly but he's still very thin and now I believe he is anemic from blood loss due to a recent change in the polyp. So he goes back to the vet again this week for a new procedure to try to stop this awful cycle. It was also mentioned that he could have a stomach ulcer that is irritated by the blood he swallows from his polyp or even food. We have tried giving 10mg famotadine (like Pepcid) daily to help but it hasn't seemed to make a difference so we doubt that's the issue. However, it's why I suggested looking at your girl's upper digestive tract. I KNOW goats are not cats, it's just an anecdote to try to get us thinking outside the box (goat).

Would an infection or possible kidney issue cause a goat to go off her feed like this?