While she may display some sensory issues, that would not explain the range of symptoms she displays. It would be prudent for her parents to arrange a thorough developmental evaluation, preferably by a developmental pediatrician. You have chronicled an array of symptoms that are indicative of some serious developmental problems in the sensory, motor and emotional spheres.
Lethargic/low activity level most days. Some days she'll be very happy and laughing all the time and dancing... but those are much less frequent. Her nights are varied - some nights she will sleep happily in her own bed or her parents' bed and other nights she will be up until 4:30am and still not be tired until regular nap time (1pm) the next day. Sometimes she will tire very easily too. A walk outside starts strong and by the middle of it she can't seem to pick up her feet very much and walks very slowly. Also if she is standing for a long period of time ("long" meaning more than 15 minutes) her legs will sometimes get shaky. One time she was at the sink playing in the water for abotu 20 minutes. Afterward, one of her knees kept giving out. She tried to walk and fell every time after a step or two. It looked completely involuntary and she didn't cry but seemed anxious. It went away after about 10 minutes.
Always wants her special blanket and to lay down. Some days it is constant. When she touches her blanket she also ***** her thumb automatically. Often I can't tear her away at all and she has no interest in activities.
Doesn’t like to cuddle a whole lot, but does sometimes, more lately than ever before (her mother reported that last part).
Afraid of being on the counter/edge and in the air sometimes. Other times she really laughs and enjoys being up in the air. Very fearful of spinning when in computer chair. She actually seemed to hold her breath and seize up when that happened, it was very odd. She hasn't done that since and enjoys spinning in circles on her own when standing.
Usually crabby without a particular reason why, hard to soothe.
Tell no and really takes it badly, even without a raised voice. She will throw whatever she has to get rid of it even if it has nothing to do with what I said “no” to. Gets easily frustrated with a toy and throws it. If trying to help her with a toy (i.e. show her how it works) she thinks you’re taking it away and gets very upset and refuses the toy when given back to her. This happens several times a day and is really frustrating.
Mostly enjoys painting with paintbrushes. If she uses her fingers or sponges and gets paint on her, about 10 minutes later she starts SCREAMING. Lately she has been able to communicate the problem by showing me her hand and saying "ew" in between the sobs. Before she would just lose it, hit her head on the floor and scream. I think she also hated the paint on her skin then, she just wasn't able to tell me.
Licks her food and has to be reminded to actually bite it, but does pretty well after a few times asking her to bite it.
REALLY hates the wind/getting blown in the face. If I gently blow her face she seizes up a bit and turns away rubbing her face and whimpering a little.
Short attention span some days, other days can focus on some things. Mostly if her sister is doing the same thing. She constantly has to be around her sister, copy her, follow her CONSTANTLY, will immediately leave an activity if sister even so much as gets up to get scissors, etc. Loses interest in activity pretty easily. She will do something for a few minutes and then search for her blanket. I've kept her blanket out of sight for a while now during most of the day. She will still search for it and once she realizes it's not there, she will lay her head on the couch or find something else to lay on/put against her face and suck her thumb. Sometimes she will lose interest after a few minutes and instead of going to lay down just wanders about the room walking and walking and walking but never picking up anything to do, when there is plenty laid out for her to do.
What do you think??? Thank you very much!