if she's that lethargic - you may have to mix up a solution of baking soda and water and squirt it down her throat with a (needle-less) syringe. you usually give them a bowl of the powder for them to eat when needed. this will help restore the acid balance in her tummy if she ate too much grain or is bloating. (big big round belly up high) (wormy belly is saggy and bloated down low - which brings me to... worms...)
is she skinny? can you feel all the bumps down her back prominently? a big belly doesn't make a fat goat. look at her gums - are they a nice rosy pink, or are they pale, almost white? in a black skinned goat look at the underside of the eyelid. if so it could be a sign you have a worm problem. i know you said you wormed her recently, but if you use the same wormer every time, they can build up resistance and the population can spike quickly - making a very weak and sick goat that cannot get back up once knocked over. you need to get her to the vet or do a fecal egg count to determine if it is a worm problem. if so, you need to give her something to kill the adult worms NOW! they can kill quickly. the vet has the meds to do that - but I'll warn you - their not cheap. to perk her back up mix up a 1 cup solution of electrolytes and dissolve a packet of instant coffee into it. try every few minutes to see how much of this you can get down her. the more the better - you will know when it's time to wean her off of it when she's been up the last 2 nights and is very hyper.... : )
also check her hooves - the outer hoof shouldn't be much longer than the inner pad - over grown hooves CAN make a goat walk on her knees - but so can being too weak to stand back up.
jennifer