Doe with mystery illness

Got a doe that we have been dealing with issues for a while now. Last year she got severe diarrhea mid-summer. We knocked her down and gave her draxxin, wormer, and probiotics. She cleared right up until about the same time this summer. Same thing, sudden severe diarrhea for no known reason. No change in diet or pen. This year she is nursing two fawns, last year her fawns were pulled for bottle feeding as she had not taken care of her fawns the previous year. We knocked her down as soon as this happened which was about a month ago. Have her draxxin, wormer and vitamin b injection and probiotics. She again cleared right up and looked great for a short time. Now she has soft poop but has dropped probably 30 lbs in the last 2 weeks. Her ribs are all showing, her tail is sunken in and her hair is falling out. Knocked her down again and repeated everything except the wormer. Her belly was soft, but very sunken in. She is getting very weak and lethargic. At a loss for what to do for her. Thought maybe she ate some kind of foriegn object, but wouldn't her belly be hard then? Any ideas appreciated. I think our time is running out with her

Thanks for the advice. To update, so far she seems to be making some slow improvement. She won't let us get close anymore, which I take as a good thing, as she at least has the energy and spunk to know she doesn't want to be darted again. I do have some metronidazole in pill form. How much were they giving of that? If she continues to have a problem, might give that a try as I can hide that in some treats and give it without knocking her down again. I know in people and dogs that can do wonders for gi bugs. We have roasted soybeans in our grain mix but maybe when she's eating a little better I will get some extra to add for her too. She also has nice thick clover too, so if we can get her eating again she should have no problem getting some weight back on.