"so are you" versus "so do you"

I recently watched a tv drama. There’s one dialogue that I don’t quite understand. The character said, “She needs help, so are you.”

I just want to ask why she didn’t say “She needs help, so do you.”

I’ll be glad if anyone can help.

Hi Rowan,

It sounds to me that you may not have heard exactly what the character said. On the face of it, as you write, it should be: She needs help, so do you. Possibly the sentence could have continued like this: She needs help so, are you going to get her some help/going to do something about it?

A