Hello,
Welcome to the ehealthforum and I am really glad to help you out. one possibility for your symptoms is sleep paralysis. which is a period of inability to perform voluntary movements during sleep.
Patients often complain of inability to move the trunk or limbs at sleep onset and for confirming the diagnosis, polysomnography or sleep study is often required. I suggest you to get it evaluated from a sleep specialist. Till that time, exercise regularly, reduce stress and get enough sleep.
I sincerely hope that helps. Take care.