what happened with the regurge exactly? was it immediately after feeding, or days later? sorry, my reading apprehension is lacking atm.
at that weight, you have no needs to worry or rush to feed. let their body readjust and relax; digestion is super stressful on a snake.
it sounds like you have quite a few variables regarding the feeder(s) in question which makes the source of the problem hard to pin down: brown water, wet rat, hole in bag,
not to be redundant: have you triple-checked husbandry?