Please help: A mom stray cat recently gave birth to 3 kittens, now she's not eating for 3 noticeable days.

A stray cat gave birth at my parent's garage. Her lips seem to be swollen with foul smell. What could this be and what should we do?

* Species: Cat
* Age: 1-2 yo
* Sex/Neuter status: Female, postpartum period
* Breed: Tabby cat, multi-color
* Body weight: Looks under weight
* History: No vaccine, no vet history.
* Clinical signs: Swollen left cheek, foul smell, no appetite
* Duration: 3 days
* Your general location: Manila, Philippines