My 4 yr old dd2, seems to suffer from anxiety, in some ways she is happy, confident and very popular at school. But when she is unsettled or anxious, she freaks out. Since having them myself I would say it is like a full blown panic attack, she goes cold and sweaty, her eyes look bloodshot, she looks as though she has lost her way, it is so upsetting.
I would say it started for her when I had ds, a year ago. I was away for 8 days as he was in scbu, and she often talks about it. After I cam home, we moved house and her older sister started school. I think the combination of things led to her being very unsettled, and she started having enormous meltdowns if we went a different route home from school, or town. If we went into town, she would only walk on one side of the road, or go to one shop. She stopped wanting to leave the house. It was awful, dh had to work different hours so he could do the school run, and I had to get a double buggy so that we could go into town with her. Even then she would rip the straps off, and throw her self into the road if we were doing something she didn't want to do.
She is a lot better now, but still has anxieties about going to the toilet (she will not go,until she is practically shaking on the floor), she also has trouble sleeping, I end in her bed a lot, and she is up for the day at 5.30.
I worry sick about her, and spoke to the gp, but she felt that we should see how she gets on at school and take it from there, maybe refer to a child psych if the problems continue.