I'm still very new, and honestly feel like I always will be, but I've had to deal with a few things so far, and I'm emassing my medicine chest:
CMPK- (have stuff to mix it up)
Aspirin- regular adult human stuff for pain
Vit E
Tums (calcium if needed)
CD/T
PenG (haven't used it yet)
Vet Wrap (used it on the dog

)
Sulmet (used it on chickens for cocci, also supposed to work for goats for a few things)
Iodine (dipping navels, wound care)
Ivermectin- paste form, also worm my chickens with it
Blu-Kote- haven't used yet, got it for the bottle babies when I disbud
I also have tetracycline which I have used on the chickens, but personally I think it is crap as an antibio, and definitely not something thats good in an emergency.
I also like to have pedialyte on hand for emergencies, but don't have any right now. It's great if you have someone not eating and that starts getting the shakes (from electrolyte imbalance). Also good to have some other stranger stuff on hand like molasses and corn syrup, and of course baking soda.
When my disbudding iron comes in at TSC this week I'm picking up the other cd/t immun. (anti-toxin? The emergency use one)