| Sometimes this can happen because the mom is licking up the pup's butts and feces. It can also happen because she may be eating a huge amount to feed the pups, and its just a bit much for her system.
You should be helping her feed those pups now, get some of her kibble and add warm water to it to soften it, make it a bit soft and sloppy, so they can manage it, and put a flattish low bowl in with them a couple of times a day. You can certainly add a touch of canned food, I mean just a touch, and/or a tablespoon of skim milk powder too, to get them chowing down.
Mom may try to instinctively eat this too so take her out and keep her out while the pups have a chance to start eating. Do check with the vet but you have to be careful of what you give the mom for diarrhea since the pups will get it through the milk. I would play it safe and give her only kaopectate, four or five times a day if need be, but no immodium unless you check with your vet, as that can be dangerous for the pups. People swear by pumpkin, I've never used it so don't know.
If you start helping feed the pups, chances are the mom's stomach will settle on its own just from not eating puppy poop, or not eating such a lot of food. Remember at 5 weeks, they're just going to start to learn to eat, so just get out the camera and don't fuss, they're going to walk through it, etc, etc... keep a sense of humour ! | 
