They put your chin on an antibiotic. It's to fight infection. If your vet was competent with the amputation, there wouldn't be any swelling. I've never seen more than a modicum of swelling after an amputation.
She needs pain meds. You need either Critical CAre or Essentials for Life. Since you're in TN, I would try contacting Tanya on here and have her overnight you some Essentials for life. My chins like it much better than the Critical Care. It's very fresh smelling and looking. Pellets with water is just mush. I wouldn't eat it either.
For now, grind up the pellets in a blender, add some 100% pure canned pumpkin (not pie filling stuff), and then add just enough water so you can get a thickish paste that will go through a syringe. You need a large opening syringe, like a catheter tip. A little one isn't going to work.
When you go to the vet on Monday, and I seriously stress going today instead, have him give her subcu fluids. IF she isn't eating, I doubt she's drinking. A chin that doesn't drink, will not eat, period. Get her hydrated, get a proper hand feeding formula, and get her eating.