Care for no longer nursing cat

I am fostering a kitty that gave birth to 5 healthy babies, 5 weeks ago. She has had terrible diarrhea the whole time she has been with me (6 weeks). She's been to the vet several times, and she has not responded to any of the suggested treatments, (high fiber diet, probiotics, pumpkin, chicken and rice). The vet suspects she has a lingering infection or parasite. She is currently on flagyl and panacur. Because she cannot pass this into her milk, we have had to separate the babies from mom in separate rooms. The babies seem to be okay, they eat on their own, and don't cry as long as we play with them. But the mom wanders around crying, and her nipples seem very full. Is there anything I can do to relieve her discomfort? It looks like milk engorgement.

They can be reunited once she finishes her 7 day course of flagyl, but by then, the babies will probably no longer be interested in her milk. 

I bet momma kitty is miserable with her engorged teets.  I would imagine she is missing contact with her babies, too.  I'd ask a vet if there is a way to pump and discard the breast milk to relieve her discomfort but also ensure that the milk still comes in after she is done with the anti-fungal medication Flagyl, just in case the kittens can/ want to nurse still.  It may be a time-consuming undertaking to do this as it will need to be done multiple times per day.  I feel it's important for them to still do this type of mother-baby bonding.  

I'm not sure if vets prescribe something to dry up the milk as is given to us humans, but it's a question you can ask your vet.  I'd ask about using ice or cool moist towels to help with momma's discomfort.