What could this be? (my son)?

For the past year my son has been sniffing through his nose constantly. its hard to explain. like he moves nose and breaths through it forcefully like when someone has a cold and are congested. but he doesnt have a cold. he also blinks his eyes when he does it. i told him to stop but he says he cant. He cant controll it. I dont know if this is a medical problem. My sister said it could be tourettes but i dont really know what that is.