Daytime body jerks, unsure if it could be stress/ anxiety related or lack of sleep or something more serious

Probably anxiety: High levels of stress and anxiety can produce muscle twitches. If your insomnia is severe, you might take your loratadine at bedtime. You are very young to have severe neurological disorder, but if your symptoms persist have your doctor refer you to a neurologist for an evaluation. Regular moderate exercise like walking can help you feel better, try to schedule regular walks with a friend.