sounds like a regurge but it is imposible to be a regurge if there were urates in it too. It sounds like some kind of diarrhea . I've never had my boa or pythons regurge , but I will tell you that it takes about a week for my snakes to digest and they usually poo in week and a half to two weeks after feeding. Make sure you don't handle the snake for about 2 days after feeding and check the temperature. They need a good warm spot when digesting. If temps are too cold the food literary spoils inside them without being digested, so check the temps. Hope all works well if that keeps happening when temp is right and you don't handle after feeding then call the vet . Hope all works well