Severe torticollis in an 8mo, help!

Hi all. I'm work in outpatient neuro and see a handful of pediatric patients. We get a lot of torticollis, but mostly in 2mo-3mo babies. Usually I can give parents some stretches and they are good in two visits. I have an 8mo right now with severe torticollis and he is so resistant to any stretches. He hates being stretched at therapy and at home. He's doing okay with milestones and can sit up IND. He is able to scoot forward on his belly but only using the LUE and RLE. I've been trying to get him to stretch himself a little with side sitting and lateral rocking on a ball to encourage active L side bending. His R trap is visibly tighter/bigger than the L side. For the SCM, I'm having more difficulty. Right now, I just put gentle pressure on the SCM while his head is turned to the R. Obviously, I'm working on his UE/LE use and coordinatation but more concerned with his neck. I'm the only peds therapist at my clinic and I've never seen torticollis this strong before.

Any advice is appreciated!!!