HELP! Worried about my 15 day old kitten.?

Whatever you do, do not pick up her kittens and take them away from her. That makes her VERY uncomfortable. My cat recently had kittens. The kittens will usually come to the mom. If she gets up and walks away, she probably needs to go to the bathroom, or get something to eat and drink. Cats are super protective of their kittens. Also be sure and watch the mom around any other cats or animals. My cat started attacking my 20 pound cat. Even started attacking my german shepherd! Don't worry about the kitten not drinking though. The mom has got it all under controll. Try and get the kitten and mom in the same room, for a long period of time. Everything seems normal from what you wrote.