How on earth you get such an idea to do ultrasound therapy on neonates? For ultrasound is contraindicate to be application in zone of the head (zone of highly differential cell) to adult people and yet you want to do it on new born baby (with little or no barrier to ultrasound)?
You have so much appropriate methods to threat torticolis, such as kinesytherapy and stretching as you sad, and if you want to treat hemathoma, there is electrotherapy (EF) and heat packs (before stretching, of course).
I believe this is not new for you because this is the protocol that exists for quite period of time but if you have some question about this if I can I’ll be answering to you, just PLEASE DON’T DO ULTRASOUND THERAPY ON BABY!