Help! My kitten its very sick!!!!?

My kitten is about 5-6 weeks old. She was abandoned and I have been taking care of her for about a month now. She has been fine since ive had her. But all of a sudden tonight I try to feed her and she won't eat. So I let her sleep thinking ill just try again before I go to bed. When I try to feed her the second time I notice she has diarrhea and looks like she can't hold herself up. I can't tell if she is just sleepy or what. Shell move then just lay right back down. She is normally playful all them time. Please help. I don't know what to do and I can't get to a vet right away.