answer:

I will start with... Perfectly normal.

Now the explanation.

The formula at 3 weeks has far been out of her system.  so that's not it.

Between 4 and 6 weeks the colostrum starts leaving the breastmilk. Most people think colostum is only in the milk for the first 3 days. but it stays much longer even when the milk comes in, and mixes with the milk. The colostrum has a laxative in it , which makes the baby poop ALL the time.  then , it slowly starts leaving between 4 and 6 weeks and most often is gone by 6 weeks. which in turn, then makes it much less frequent for the baby to poop, its much thicker and they can often go 10 days easily without pooping at all because the breastmilk is that digestible.

This thickness causes a little more odor, and it makes it appear that pooping is painful. It is however not painful, the baby isn't constipated. She is frustrated because for the first time in her life she has to learn how to use her own bowels to make a movement. Just like learning to walk, she needs to learn how to poop on her own. control it with her own muscles so that she can then control it at night etc... you will notice that pooping at night will get less and less frequent  etc... its  hygiene thing as well.

She will work through this frustration as she learns how to control her bowels on her own, ( which we want her to do... so don't try to help her out with suppositories or anything )  and as time goes by she will get better at it and it wont take so much work etc. You can help with gas by using gripe water from a whole foods store, or bicycling her legs etc... massage with a light oil on her belly going downwards to get the bowels moving a little more might be helpful.

But know that its very normal. the only thing you need to watch for is if her tummy becomes very hard, even while shes resting and she seems like shes in terrible pain even when not trying to make a bowel movement.  that could be an obstruction. but Most often, if she has any bowel issues you would know by now.

She seems right ton target from what you've told me... hopefully this things will help you get through it some... but it is normal... just a little unpleasant from her perspective of having to learn an uncomfortable thing and a little for you having to watch her and smell the gas :)

I hope that helped!
Ruth Kraft
www.honoringwomen.com