2 Year old tensing up legs. Does anyone's child do this too?

I'm an OT and mother of twin 2 year old girls who have demonstrated developmental delays. They are getting early intervention, pretty much everything offered! They are going to also see a developmental pediatrician in August. We believe at least one of my girls has SPD. Some are talking Autism but I don't always see that. She has problems with eye contact, speech, playing with other children, is awkward in movements but will engage socially with older kids and me. She used to do a lot of rocking, head banging but since February, she had started laying on her stomach and tensing up her legs. It has evolved to where she kicks one leg up and brings it across the other leg. She does this quite often all throughout the day and sometimes for several minutes at a time. She gets herself all hot and sweaty from it also.

We've tried weighted/compression vests, trampolines, etc. but nothing seems to fill the void. None of her therapists have seen this before. I am wondering if anyone else has a child who does this? I was looking into tics and Stereotypic Movement Disorder but nothing mentions leg tensing as a symptom. Was also thing about OCD as well. it's really interfering with her learning/doing anything. Now she also likes to hold two objects and stare at them when she does it.