Im really worried about my baby cousin! please help?

i have been taking care of my baby cousin Ari since her parents died and i've noticed some odd things. for one she never dreams, unless she's having nightmares. and she doesnt sleep a lot although she's only four. i'll put her to bed at 7 and she'll still be up when i go to bed at 11. and she scared of old people (she thinks they come out of her closet) and she's terrified of fire. i didnt even know she had ever seen a fire (since her parents never took them camping and didnt have a fire place) until i set up one in the fire pit for us to roast marshmallows. she started screaming at the sight of it and she had nightmares about it for a week. im really worried. is this symptoms of post traumatic stress from losing both her parents or is their some underlying issue going on here that i should worry about? or am i just being over protective and freaking out over nothing?