This is difficult as there are a number of things this could be from the symptoms and you have had 3 different vets give 3 different diagnoses.
Firstly the original symptoms of being uncomfortable or losing balance would suggest possibly an ear infection (treatment antibiotics) or ear mites. (treatment ivermectin and ear drops) . Mia received an injection which was probably baytril (or other) antibioitic - but this would not be enough unless she received a proper course of antibioitic over at least a week to wipe out infection
Next she is seen by another vet who notices she is not pooing/eating properly. The hair shedding etc indicates she is under the weather (and again could point to mites). This time she receives syringe food (which is imortant to keep her guts moving as already stated by other posters on here).
Having rung Apex, they diagnose possibe bloat over the phone - this could be the primary or a secondary issue (secondary because it has been caused by the anitbioitic/not eating). However if it is the primary issue, (which it could also be based upon her earlier symptoms) then the bloat could be caused by an obstruction and the best treatment will depend upon the cause.
The bottom line is that your piggie is very poorly and it is vital that she sees a cavy savvy vet tomorrow....can you get a friend to take you to Apex? At the very least she needs a continuation of whatever treatment she has previously been given - be that a full course of antibiotics, gut stimulant or whatever injections - and a firm diagnosis as to what the problem(s) are.
It's also important that you syringe feed her until you get to the vets to keep her guts moving. This can be quite daunting at first and everyone has their own way of syringe feeding.I put the piggie on my lap on a towel with head pointing to the right (I am right handed) With my left hand I cup her face/chin, lift her head slightly and then guide a 1ml syringe (with end cut off) into the side of her mouth behind her front teeth and dispense 0.2ml at a time, giving her a chance to chew/swallow in bewteen. After a couple of mls I then syringe 1ml of water to rinse her mouth. If she son;t eat the mush - you could try fishing out the pellets from the Wagg crunch and rehydrating those with boiled water and allowing to cool as described above
Also you need to alleviate the bloat (furry friends will talk you through the gripewater/infacol - buy at any main supermarket in the baby section). You can also try massaging her tummy very gently. With her head pointing down/away from you, cup your hands round her tummy in front of her hind legs and very gently massage her abdomen whilst she takes her wieght on her front feet/resting on your legs. If her tummy feels taut rather than squishy(and sounds hollow when you tap it with your finger) then that is a sign of bloat.
I do hope you can get her to a vet tomorrow and get a definitive diagnosis together with the correct treatment.
HTH
x