Terry Dunham is absolutely spot-on about the fact that you should not be keeping the snakes in close proximity right now due to the problem with the other snake.
Here are a couple posts about this that I have posted over the years regarding regurgitation, and what to do about it.
I would also suggest that you print this up and bring it to the vet with you just in case he/she is not very experienced in reptile medicine. A swab of the throat, and a "fecal floatation" are very key for absolute diagnosis and treatment, but the three posts I am giving you here refer to the treatment of regurgitation, and Over the course of years here, I have had several people thank me for saving their snake's lives when they followed these steps to the letter.
Below are the previous posts I have made to a few others regarding the treatment......
Good luck!
First,….DO NOT attempt to feed it more meals until it has been looked at, I strongly suspect it has some nasty intestinal bacteria from the putrid previous meals. I would imagine a two-dose regimen of Flagyl(metronidazole) could EASILY be all that is needed here. This will kill the bad protazoa/pathogens as WELL as the GOOD bacteria that is needed for proper digestion, so STOP offering it any food until the snake has been looked at and helped. Feeding at this point will only lead to more regurges and a DEFINITE downward spiral that could easily end up killing it. Offering food at this point is the WORST thing you could do right now until you tackle the intestinal problem.
Hopefully the vet will know the proper course of action, but MANY vets don't know diddly squat about reptile medicine whatsoever. The snake should get a dose of of Flagyl at the rate of 50 mg./per kg. of body weight given orally, and another follow-up dose 10 to 14 days later. NO FOOD should be offered until at LEAST a good week or so AFTER the last dose so the snake can replenish it's vital acids, electrolytes, enzymes and gut flora before being fed again. And when it IS fed again, they should be very small meals for a while to make certain they stay down and are digested properly, you cannot afford for this to happen any more whatsoever.
After several VERY small meals, you could GRADUALLY increase the size back to the size prey it was normally eating, just make sure you never offer these gigantic meals again, that is of no benefit at all, and usually only makes it tough on the snake's system as you have already found out.
Sometimes snakes develop this from fouled water too, so who knows, but I would bet a dollar to a donut some Flagyl at the proper dosing will take care of this. Flagyl is very reptile friendly too!
good luck!
~Doug
Post #2 on regurgitation
I strongly suspect it has some bad intestinal bacteria and the meal simply putrified instead of being digested. This can be caused by a number of things, fouled water being among the top causes.
Tell her to get it dosed with Flagyl(Metronidazole) at a dose of 50 mg/kg of body weight, and another follow-up dose in ten days. DO NOT attempt any more feedings until at least a week after the LAST dose, as this kills the bad bacteria, AND the good bacteria needed for proper digestion.
I have done this myself with several animals in the past. Many years ago one of my young Honduran milks had an intestinal bacteria problem, and would regurge even a VERY small meal. Dosed with Flagyl, and problem immmediately GONE!.....forever!!
good luck, ~Doug
Post #3
In addition to what Tim has said,..it could have easily drank some fouled water in the previous owner's care that lead to it getting undesireable pathogens in it's intestinal tract.
If it is kept in the mid to upper 80's on one end ONLY of it's small enclosure so it can thermoregulate, this should have been fine to enable it to properly digest it's meals. It is NEVER a good thing when snakes continue to regurgitate,..especially a tiny hatchling. This can take a heavy toll, and lead to it's death very quickly if not taken care of ASAP!. If it does not hold down a VERY TINY meal next time when fed(wait 10-14 days before doing so!), then I would strongly suspect the problem to be bad microbial pathogens in the gut, and it needs to have a dose of Flagyl(Metronidazole) administered at 50 mg.per kg. of body weight, then another follow-up does of the same 10 days or so after the intial one is given to kill the bad pathogens. If this is done...DO NOT attempt to feed it AT ALL during this time, as the medication will kill both bad AND good flora in the gut that it needs to properly digest. You must wait approx.7 days AFTER the last dose is given so the snake's stomach can get re-gain the acids, enzymes, electrolytes, and good bacteria needed to digest, or you will simply start the ugly cycle all over again.
If it does not hold down it's next VERY tiny meal when given in two weeks, the snake will very likely be dead without the proper dosing of the Flagyl. This stuff works wonders when applied to the correct circumstaces, and these could EASILY be one of them. I have administered Flagyl to snakes that have had this problem before in the past, and it works like magic!! Several years ago, I had a 300 gram Honduran start regurging meals, and did it again no matter how small the mice were. After I gave it the proper dosing of Flagyl,....BAM!, problem gone FOREVER!
hope the little snake gets better, because it's life all depends on what you do here,...simple as that.
good luck!, ~Doug
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"a snake in the grass is a GOOD thing" 
my website -Serpentine Specialties
