My apologies your question was not responded to in a timely manner. I just came online now and saw it posted.
I'm sorry to hear that your pup Frankie was behaving strangely last night, confused, flinching at motions and seeming off balance. My hope is that she is feeling much better today, but I did want to caution you that this may be related to her eating an apple she found in the backyard.
Old apples may rot and ferment, and when that happens ethanol forms. If your pup then eats the apple the effects are like you or I drinking too much alcohol. No wonder she was behaving strangely, she was likely inebriated. Dogs do not handle/metabolize alcohol well, and a small amount can make the pup very, very sick. This can be deadly for your pup if she eats enough fermented fruit. Signs of advanced ethanol poisoning include lethargy (sometimes severe), incoordination, slowed breathing and heart rate, metabolic acidosis (low pH in the blood and body), and possible heart attack. If left untreated, this can result in the dog's death.
Treatment is supportive care including fluids, respiratory support and medication for heart issues if present.
My hope is that since your pup only ingested one apple she is feeling much better today, but I want you to be aware of the possible cause of her symptoms. If you have an apple tree in your backyard it is important that she not be allowed access to the fruit. Short of cutting down the tree you can fence the tree off, and make sure to pick up fruit the same day it falls.
Again my apologies you didn't get a quick response but I wanted you to have the information for future reference.