Need help: newly very defensive and refusing to eat due to stress

[Hugsplox]

Hello and welcome to the forums!

Fortunately, if you can call anything about your situation fortunate, it's pretty clear to me what the issue is, and you've said it yourself, stress. You've got a new snake, who's moved into a new home, and before she's had time to settle in and acclimate to her new home, you (rightfully so) take her out and take her to the vet. Then there's the oral meds and numerous feeding attempts, and the continuation of handling even though she clearly isn't up for it yet.

My advice is to stop everything except the meds. Don't try to handle her don't mess with her at all until she has time to settle in. That's going to be rough because you're having to give her the meds, but other than that I wouldn't try to interact with her at all. These snakes live 20+ years so you have plenty of time once you get over this hump with her. You really don't want to handle a new BP until they've eaten 3 times for you back to back. As far as building trust, that's not something the snake can comprehend. Some keepers may disagree with me on this, but I think most reptiles just eventually disassociate handling with danger so they tolerate it, but the snake doesn't get anything out of it. If I just never handled one of my snakes they're not going to get depressed, if that makes sense. Handling is for the keeper's benefit not the animal's.

Lastly, BPs can go awhile without food, so if she's not losing weight, she's probably fine. I would stretch out your feeding attempts, meaning if she won't eat today, don't try to feed her tomorrow. Most keepers suggested waiting 1-2 weeks between feeding attempts, and I think that's the route you need to take. It may be worth waiting until after she's done with the meds though, and has had some time to settle in and relax.