Glad she is starting to heal
the loss of appetite could be from the antibiotics, and or if there was infection present. Medications can put gliders off their food just like it can for humans, it's not that uncommon for a glider with a neck wound or any wound to lose weight.
you can give her some full fat yogurt with live cultures for a treat between doses of antibiotics. The yogurt helps to restore the good guteral bacteria that the antibiotic kills off and might help settle her tummy n increase her appetite. Make sure there are not artificial sweeteners and no low fat or no fat. Yoplait makes a full fat, normal sweetener yogurt, you can use one with fruit in it as well.
What diet are you feeding?
how much does she weigh?
head shaking, the medication probably tastes bad to her. When one of mine did that I was super concerned until i was told even if the medicine is flavored it might taste terrible, I tasted it, sure enough it was terrible lol.
The head shaking was a good sign that she actually got the medicine in her even though she shook some out of her mouth after she swallowed.
It's a pretty 'normal" thing for them to shake their heads from meds, i actually have a few that have done it and more than once I've had to load another syringe to give a full dose if I knew they didn't swallow any of it.
I have one girl I would take a kernel of corn squeeze out the middle n put her dose in the the skin of the kernel instead of fighting to get her to swallow the dose from the syringe, she loved corn so much she'd eat the meds with no fuss
She also lost a bunch of weight, from a neck wound that required stitches, she gained all the weight back gradually just from her normal diet and her body healing.
As far as meal worms, a lot of gliders won't eat the shell, they eat the middles and discard the rest, sometimes by flinging it, sometimes by shaking it out of their mouth.