I tend to disagree that a mouse crawler is too small for a boa - it totally depends on the size/age of the boa. My baby was only 6 weeks old when we got her and she most certainly should not have been eating anything bigger than a crawler. She ate those at 1 a week for about 2 months and then we upped her meal to 2 per week. She is now 8 months old and eating 2 hoppers per week. She will go up to weanlings in January. She is thriving and getting very big.
BUT that's really neither here nor there at the moment. Sorry about that. To the OP, you should not be feeding every 4 days. Feed only once a week no matter what size prey item you are offering. Definitely wait about 2 weeks before feeding again. Boas can sometimes have a tendancy to regurge and can become chronic so we certainly want to stop this asap. Do what others have suggested: double check your temps and wait the 2 weeks, then offer 1 crawler. If she keeps that down, I would offer a crawler again once per week for the next couple weeks too. Keep her meals at the same size for awhile until she is consistantly keeping them down. Then you can safely up her to hoppers. A few more crawler-sized meals will not hurt her. Regurging again could.
This is just my .02 cents, but it's what I've been told by several very honest and reputable boa breeders and hobbyists. Good luck and keep us posted!
Thank you so much, I really appriciate all the help, She is about 80 grams now and then she was what I considered a bit small when I picked her up and was a bit dehidrated then also. I was thinking that a rat pup would be good soon also.