Hi, I don't know if this will be helpful but let me tell you about my son who has sensory integration disorder. Sensory involves the nervous system like add/adhd and symptoms can look similar. He is a "sensory seeker" and he spins to calm himself, bounces and rocks---------- lots of movement. Google sensory integration disorder and see what you think---------- particularly sensory seeking and also regulation/modulation. Self soothing does not come naturally to some kids.
good luck
Are you taking any meds for the ADHD , sometimes they need adjusting or changing as they can have side effects, may be a good idea to make a visit to the Doctor and ask him what he thinks, it is possible you do this as you say to calm yourself ,I must say I havent heard of it as part of PTSD but it could well be good luck .