Let me first say that scabies is extremely contagious, and can be transmitted to humans, and vice versa, which is probably why they reacted that way. They may suspect that the dog got it from you. (Which in their frame of mind is quite possible, since they don't know your state of health.) I believe you that you don't have it, but they don't know for sure. That said... it is still VERY UNPROFESSIONAL for them to let you see their reactions, even if they coudn't help it.
For that reason, and for that fact that they didn't even suggest giving your dog anything to help it relax, (such as Benydryl or a related med) I would definitely go to another vet. Scabies is extremely irritating. Also, just as a tip, whenever you are at the vet, and you have a question about painmeds, or ANYTHING, ask. Yes, technically, you shouldn't have to ask, but a vet can't know your concerns unless you do.
I personally am not going to prescribe a med, since I'm not a vet, and I don't know your dog. I don't want to risk aggravating the condition more, or cause an allergic reaction, but I strongly urge going to a new vet.
Good luck, I hope this helps you and your dog!