Help! My guinea pig is running back & forth in her new cage making a squeaky sound!?

Okay well first off, I'm pretty new at this whole guinea pig owner thing so yeah. My first one I got as last month who died 2 weeks later. But since I got a free one, I bought her a cage. I got her about 2 weeks ago, shes a baby at least so they said and she is very little & less furrier then most guinea pigs I see. But anyways I'll get to my point, she just got her cage today shes been fine al night but she just woke me up at 4 am doing this LOUD squeaky sound & then she ws running back & forth. Running in circles going in hideouts then coming back out. She still is doing it! Whats wrong with my Piggy!? She isn't dying like the first did, is she? Oh by the way I got her the Midwest Interactive Guinea Habitat Plus cage.