I commonly see regurges on day 3. It takes the pink (or whatever) time to decay, and then it comes back up. It decays because the snake is too cold and can't digest, the meal is too large and can't be digested before it rots, or the snake is blue and something must interfere with digestion, sometimes, in that state.
Do you have a weight on him?
And you need to skip the next planned meal, and then feed a meal half the size of what he regurged. How big were the pinks you fed? It's a big jump to go from one medium or large pink to two. I've gotten away from double pinks and am just gradually increasing the size right through the range of pinks up to extra large pinks to small peach fuzzies and so on. I guess it's a luxury to buy pinks and fuzzies by the hundreds so I can sort them like that.
Okay, after skipping the planned meal, you are effectively not feeding him for 7-10 days after the regurge. Get Nutribac if you can, and put that on all future meals for several months. When you feed, from now until he is on weanlings or adults, always slit the back and if you can, the skull of the prey.
Make sure he is warm enough. He needs the center of his UTH, under the substrate, to be in the 84-86 range.
I would do everything I could to avoid feeding him when he is blue.
If you can't vary the size of the pinks, don't go from one to two. Do one, one and a half, one and a half, two.