I'm a nanny not a parent. please read

Emma

so to start off, I am a nanny for 2 little girls. almost 5 and 3 and a half. both girls had to go to speech therapy because they weren't talking at all. the oldest was potty trained and a little over 3 years old. the youngest WAS potty trained for months and the last month she has been choosing to pee her pants. She will pee on the couch, her bed, my car, the parents cars. She will pull her pants down and pee on the floor in her room. She has eatting problems now where she will ask for a certain food, I will make it just how she asks and she will throw a huge tantrum to the point where she will break blood vessels in her face from screaming. She also has started hitting her sister and thier dog. She will scream no at me for asking if she wants a drink of water(I'm not kidding). The parents don't think anything is wrong with her, I do. I have no ideas what it could be. But with the potty training regression, the tantrums and the hitting and screaming what else can I think? I work 60 hours a week with these kids. I have for 2 years. i know these kids and I know this isn't normal behavior for them. no they are not being abused somewhere. if that's what you are thinking. Please is there anything someone can think of that might be wrong with this child ? please I am in despite need to help. She is stressing me out so much, I have a constant headache.