
It's normal and she will grow out of it! There, now that I've told you what you want to hear, I can tell you she really will grow out of it. 5 months is just the age when the teeth changing is in full gear. Also, she is testing your limits. Be firm with her but DON'T hit her. There are many ways to get them to learn. One good one is time out. Just like you would do with your kids when they misbehave. After a few times, a dog learns to associate his behavior with the result. It takes time, but it happens.
Another thing that is immediate: spray bottle - fill up one with water and a squeeze of lemon juice. Everytime she nips at you, spray her nose (have it around you!!), after 2-3 times she will see the bottle and stop. If she'll get used to it, try the mint spray (the ones for the breathe). You can use a metal can with some coins in it (some say 10 pennies is just the right noise

Most important thing is to be consistant. That's the only way they learn.
Now to the important things: PICTURES PLEASE
