$50 is nuts for probing. Maybe I just have a generous vet, but when I took in 5 of my hatchling ball pythons to be examined for a respiratory infection, he probed all of them at no extra cost.
Regarding using bacitracin, while Foschi has good intentions and is telling his/her honest experience, I don't take medical treatment advice as the solid truth unless I confirm it with my doctor or veterinarian. And I mean no harm to Foschi. But you might want to check with your vet before doing any extra measures. Also, I believe I learned Baytril can leave scars. Did the vet's office do any "lactated ringers" or something like that so that the med isn't concentrated?
Your best approach IMO is going to be to ask the new vet to type up and perhaps initial a note on the vet visit receipt that states the snake's ventral infection appears to be from trauma that could have occurred xx days prior. Or something close in description. And print the pictures. Then make a trip to the vet in person with receipt, vet signed note, pictures and ask to speak with the office manager or vet at the old office. If you approach it with respect and confidence, do not be wishy washy about what could have happened, nor be preaching like "you did this, you hurt my snake, you mean person..." because both approaches would allow the vet/manager to weasle out of it.
If that attempt doesn't work, you should file a claim with small claims for all costs incurred with both vets. I believe it shouldn't be more than about $40-60 and most likely the vet will then back down without a fight. Then I would post a respectful but honest feedback on a site like yelp.com or multiple sites. Everyone needs to learn, the only way you can get experience on probing is to probe snakes, but one can't do it without enough instruction and regular practice. It is better to admit that you don't know than to pretend you do and "wing it" with a live animal or person against their knowledge.
Best of luck and I'm glad that you have a good vet source and your animal is on the road to recovery.![]()