He's young enough where you can easily do a few things at home to help out his torticollis. My oldest had it so bad his head was totally flat, his ears and eyes were misaligned, and his forehead bulged out. Our pediatrician was very laid back about it and showed us how to lay our son with his head by our belly and his body stretched out down our legs, and put our hands behind his ears and kind of massage up and down, pulling up and lighly rubbing down. And also we did alot of laying him on his back and turning his head the opposite way he favored, and sometimes having to hold it there and showing him toys, talkign to him, engaging him. Also at night after he was asleep I'd go in and turn his head. Once he was really 'out', he'd not move it back, and owuldn't even notice me turning his head.
HIs problem started as a newborn, and got really bad aorund 2-3 months. We started doing these things at home around 3 months, and by 6 months his head was nicely rounded, and now at 5 1/2 you can't even tell he had flat head.
I wouldn't advise using anything in his bed... he could move just enough to get it beside him in his face. Lots of tummy time during the day, limit time in the bouncy, carseat, swing, etc, and when he's napping, try laying him on his side with a rolled up blanket behind him for stability. Or just turn his head when he's sleeping.
Good luck... and he probably won't need a helmet.