I thought you might benefit from a step by step explanation of what someone else (in this case, me) would do if they owned this snake. I know it would have helped me were I in your shoes.
A few husbandry notes first: I would switch to paper towels as substrate. It is easier to spot another regurge and to spot poo (which you want to make sure is normal looking throughout this process). Also, make sure the temps are in the correct range (74-78 on the cool side and 82-84 on the warm side would be sufficient) and that he has plenty, if not a few extra, hides to keep him as stress free as possible. Finally, as much as I know you probably want to handle your snake, leave him be, other than for cage cleaning, until he's gone a few months with no more regurges. If at any point during this process, he regurges again, you will need to start from the beginning again.
1. From the day of the regurge, wait 10 days before offering food again. During this time, add NutriBac to the water. I generally pull the water for 2-3 days to ensure that the snake will drink the altered water when it is offered. I make sure to watch the snake drink (I 'show' him/her the water bowl when placing it in the cage, they generally drink right away) and leave the water in for 1-2 days before repeating the cycle of withholding and offering NutriBac water. Keep in mind that the snake should be handled as little as possible during this time.
2. 10 days after the regurge, offer the snake a pinky head. You can save the body for future feedings. Repeat the pinky head feeding for 3-4 feedings (once a week) before increasing the meal size.
3. Increase meal size to the pinky bodies that you fed the heads off of before. Again, once a week for 3-4 feedings. All meals should be dusted with Nutribac at this point, and from here on out for at least 6 months. If the snake is okay with eating the NutriBac dusted meals, then adding NutriBac to the water can be discontinued (and water then left with the snake at all times, of course).
4. For the next 4-5 feedings, feed small pinkies, once a week. The pinkies should be slit along the back two or three times to help with digestion.
5. If the snake has kept down all meals prior to this point (about 12-14 weeks after the regurge), the meal size can be increased to a large pinkie. Feed the large pinkies for another month, with meals once a week.
6. At this point, if you'd like to increase feeding frequency to once every 5 days, and the snake has not had a repeat regurge, I would feel comfortable doing so. Keep the size of the meal at large pinkies, every 5 days, for another 4-6 weeks. Remember to continue with NutriBac on the food and also slit the backs of the pinkies.
7. Now, the prey size can be increased to peach fuzzies or very small fuzzies, which is probably what he was eating prior to the regurge issues.
I hope this helps.
Remember, you aren't trying to put weight back on this snake for at least 4 months after the regurge. I know I've mentioned it before, but just a reminder that I'm feeding my nearly 3 year old, 130 gram (was 165g and eating large weanling mice before he started refusing/regurging food) peach fuzzies, and will continue to do so for another month before bumping him up to normal size fuzzies. Bringing a snake back the right way from a regurge (especially multiple regurges) is a very slow process.