My kitten is being weird

Chris

Lilly has always been a very hyper kitten but since she hit 8 weeks old she's just gotten really slow. She sleeps all day and all night, won't even nurse even though Jackie (momma cat) acts like she wants her to nurse and she barely picks at dry food. Her gums are a little pale but we gave her a iron supplement and it helped a bit, but not enough. She was born with 3 other kittens and she's the only one left, what could be going on with her? Jackie is kinda acting the same way but she might be pregnant again so that could explain why