First, I do have to say that I am quite concerned about your lass. Her signs at her age are highly worrying of toxicity even if a toxin could not be found (antifreeze being one that could cause these kinds of signs). As well, if those gums are whiter then usual, this does raise worries of potential compromise to her oxygen uptake (a bigger worry if you think she is breathing heavily) or even internal bleeding. Both can cause weakness, wobbliness, and lethargy. So, these would all be major worries here with Coco.
As well, further to the toxins for her signs, we could also see this type of presentation with a dog that has a middle ear infection, vestibular episode (less likely with her age), or possible polyps/growths in either region (again less likely at her age). And less likely here, we could see these signs also with brain based issues (ie head trauma, bleeds, infections, etc).
In this case, with her age and the sudden onset, I'd still be concerned about toxins with her. Therefore, if this was my patient, I'd want to have her checked any potentially treat with activated charcoal (More Info/Dose HERE) to bind any possible toxins. Or if there was any chance of antifreeze (at home or if someone has tossed antifreeze soaked meat into the yard, etc), the we'd want to consider checking bloods +/- IV fluids. Otherwise, if we could rule this out and instead found a middle ear issue, then we could all breathe a sigh of relief and start systemic treatment to address that.
Overall, I do share your concern abut Coco here and we do need to tread with care. Her agitation/skittishness will be because this is making her feel unwell and she doesn't understand why. But the other signs just raise some serious worries that we are best to cover bases on instead of allowing any risk.
PS- I have just seen your mention of bites --do you mean they look like hives (a sign of allergic reaction)? Are they itchy?