[Thamnophis]

What a story. Thanks for sharing.

Try to get some faeces from the snake and take this to a "normal" vet. Eventhough this one might have no reptile experience, mostly they can determine worm(-eggs) in the faeces.

But if the snake only has a bump and does not look ill and acts normal you might consider to just leave her alone.
She can give birth to her young in peace than.
All this vet-trouble gives her a lot of stress, I guess.