Hmmm, a feed store on a dairy..…
They hopefully will (and should) have a probiotic.
Probios is a good brand and can be given to nearly all livestock that I know of.
The powder form is great because you can mix it with juice, water, applesauce, pudding, whatever is needed to get it down. There is one for goats that like mine suck down like candy, but I doubt they will have that one there. (Goat's Prefer is the brand, just in case)
TSC (if you have one close by) should carry it too.
Your girl will probably need this to help re-establish healthy flora in the rumen and something you can give daily for at least a week.
This is one of those things that if one of my alpacas or goats even blink at me wrong or belches in a way that I don‘t like…. Down the hatch it goes.
Red Cell is usually only $15 for a gallon at most online supply places but there are also quart size bottles available for much less and something I always keep on hand.
Another possibility for iron is an iron paste made to give baby pigs (who are born with low iron) and something farm stores in ag. Areas usually have. I have it on hand and the injectable form too, but unless you are really good at doses, weight, conversions and giving injections this one needs to be handled with care.
Other supportives for weak calves and livestock are things like Dyne, Power Punch, and Nutri-drench. These can be used for goats or there are ones specially made for goats.
Another product that is good to keep around that may be found at the store you mention is Vitamin ADEB12 gel. (by Kaeco)
Vitamin B is water soluble and giving some of this gel won’t interfere with the B the vet gave you. This also has some probiotic in it, but not nearly as good as Probios or a plain probiotic powder or gel.
These are all things I have used and would use for a sick or stressed goat.
Thanks for the tip on the hooves. I will remember to have that on hand.
http://hoeggerfarmyard.com/the-farmyard/goat-health/
I haven’t checked the online health pages, but this is where I buy some of my hard to find dairy, cheese, and goat items.
Hoegger Supply Co. :: Goat...
Their catalog is free and well worth having around just to read and learn from.
Since this portion of the website is new there may be some really good info here to be found.
Hope the feed store has what you need.

Of course, you know that since you have talked about her so much, we need pictures once she is feeling better!