I don't recommend peroxide for any reptile at all. For snakes, bearded dragons and most geckos it cause more damage than it heals- it damages heathy tissue around the wound. So I would hold off on that.
A safer alternative would be betadine, diluted to a tea like colour. Don't put anything with pain relief on it at all, the chemicals in them are harmful.
I really am am not comfortable with that vets choice of treatment, and would recommend a second opinion with someone more reptile experienced.
Good luck!!