D.R.
Your daughter sons like my son! He is 6 (7 in Dec.) & he started acting like this when he was 4 1/2 & hasn't stopped. lol We always have to announce where we are going when we are in the house. If he is downstairs & my husband or I need to go upstairs for something, we have to tell him we are going upstairs for this & we will be right back. He will say ok but a minute later of him being by himself downstairs, he runs upstairs to find us but tries to act like he was coming up for another reason. Cuz he knows what we told him & that we aren't leaving him, he is fine & not to be scared but he still does it. If we don't tell him what room we are going to or if we went outside, he will call out our name & if we don't answer he starts yelling out for us & goes into panic attack mode running around the house, opening the front yelling for us. I don't even know what the neighbors think of that when they hear or see him running out of the house yelling/looking for us. lol Sometimes we laugh about it now cuz it's the samething over & over.
He is fine w/us dropping him ____@____.com once he gets out of school & he is waiting right there for us to pick him he will start to cry if he doesn't see us right away. We had to explain that it is ok if we are not there right when the bell rings. We told him there is no need to worry or cry if there are still kids there. We told him u can start to cry/worry when u notice it's only u & the teachers left (which this has never happened but we had to tell that).
We do have a daughter 1 1/2 yrs old but I don't think it has anything to do w/him sharing Mommy & Daddy. He started acting like this when I was pregnant w/her. He always wants his sister around & if she isn't w/us, he is thinking about her & asking when are going to pick her up(if someone was watching her for us).
My son is just a scardy cat like his momma. =) lol I was chicken when I was kid but I don't remember being that bad. We did get tired in the beginning of telling him everytime we were going to another room but I guess we learned to deal with it & just hope that oneday he will grow out of this. I just keep thinking that once he becomes a teenager he will probably care less about where mom & dad are. So I just try to think good that my son still wants to stick close to us as long as possible. =)
Good luck!