Injury Squealing

So about two ish weeks ago I thought my guinea pig was sick because she was squealing and had a wet bottom. Her bottom dried up after a couple days and she seems fine. She eats, sleeps, drinks, etc, all normal. She doesn't squeal when I pet her either. But, she has still been squealing but it's not like a happy squeal. Every time she squeals I look over and I noticed that my other guinea pig, which is a girl a few months younger, is always like following her around. So I'm not sure what's going on and if my guinea pigs are hurting each other...