Is the normal goat new too? It won't hurt to worm both with Ivermectin either way. Vitamin B is a safe standby for any goat a little off. Probiotics are easily obtainable from the feed store and will restore rumen health if a change in water or diet has thrown her off.
FAMACHA (the eye chart) only works for one type of parasite - the barberpole worm, be clear about that first off. Barberpoles do not typically cause scouring. They cause anemia, which is why the eye chart is helpful.
There are other internal parasites that tend to bloom along with barberpoles though, especially when a goat is stressed that do cause scouring. In addition, you said your goat got into rabbit feed which is another thing that can cause scouring on it's own.
When bringing home a new goat, I would always do a quarantine de-worming drench to deal with any stress related parasite blooms.
*Quarantine Drench - to help avoid introducing drug resistant worms
--isolate animals to barn, dry lot or a sacrifice pasture not used for other sheep
--use more than one dewormer class, one of which should be cydectin and the other probably levamisole (Prohibit).
You do, however, need to know what de-womers work (and don't work) in your area. In much of the US Safeguard is ineffective, Ivermectin is losing effectiveness and Cydectin is being misused. If you use the wrong dose, too low of a dose, the wrong product...then you're only hurting the situation, not only for your goat but for every goat owner out there by helping to create even more drug resistant strains of parasites. So, what's a goat owner to do? Err on the side of caution and use the strongest dewormer you can and use the highest safe dose on your animal. Get fecal tests done as much as possible before you chose to de-worm and do not de-worm indiscriminately.
I agree that Vitamin B is a good option for a stressed goat.
Another product to keep on hand when dealing with parasite issues (anemia related parasite issues) is injectible iron or redcell.