What should I do with this stray cat?

I've been feeding and giving water to a stray cat since it was a kitten, I was never allowed to take her in. She got pregnant and my mom allowed me to take her in since she looked like she was going to burst. The kittens are 7 weeks now and I'll have to put mamma cat back out once all the kittens have new homes. But I'm worried about her because she recently has lost a lot of weight and is looking sickly skinny.. but she eats a lot. She also continuously meows for no reason for a long time and has been pooping a lot more and she always seems to have a stink trail following her now. Anyone have an idea of what might be wrong? Will she be ok? Is she just this way cause of having kittens?