DS has been in a rock n play since about 3 weeks old due to reflux. At 3.5 months, he's getting a bit too big for it, so we decided to transition him to the crib. In the RNP, he slept 5-7 hours at a time. Since putting him in the crib a little over a week ago, he only sleeps 3-4 hours for the first stretch, 2-3 hrs for the second, then wakes every 30-60 minutes after that.
We have the safe lift crib wedge in there to help with the reflux. I also rolled up a towel and placed it in a U shape to cradle his lower body to simulate the feeling of being in the RNP. We have continued to keep him swaddled (although he manages to get both arms out almost every night now). We follow the same bedtime routine as before.
To save all our sanity, after the second waking, we put him back in the RNP. The first few nights we didn't do that, DS was a mess all day (not to mention DH and I were not functioning either).
Any suggestions? Advice? I know it's only been about a week and a half, but it's discouraging.

Re: Rock n play to crib transition
Is your LO using a pacifier? I put DD in her bassinet first for a couple week so she could get used to lying flat and swaddled her with the miracle blanket. She also uses a pacifer at bedtime which totally chills her out. I just transitioned her to the crib last weekend (she's too long for the bassinet now) and she usually gives me a 5-6 hour stretch.. sometimes longer!
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Unfortunately, I think you just have to stick with it. It took DS about 2 weeks to really get used to his crib after sleeping in the RNP for 2 months, and when we made the transition he really regressed in his sleeping for the first week. He started waking up every 2-3 hours again, instead of the 4-5 he was doing in the RNP. But, after 2 weeks, he figured it out and now sleeps very comfortably in his crib.
I would not recommend putting him back in the RNP after his last wake-up. It won't help him get used to the crib if you're eventually just putting him back in the RNP. Where does he nap during the day? It may help him get used to a flat, open surface if you have him try to nap during the day like that, too. We introduced DS's play mat around the same time that we did the crib transition, and I think it helped him get used to lying flat.