A 4-week-old female patient presents with head tilt to the right side and chin tilt to the left. A non-tender rubbery mass is noted with in the right sternocleidomastoid muscle. Her neck can be brought to neutral position and her neurological exam is normal. She is a full-term product of an unremarkable pregnancy and delivery. Which of the following is the next step in treatment for this patient?
- Radiographs of the neck
- Magnetic resonance imaging of the mass
- Refer to physical therapy for neck range of motion
- Ultrasound of the mass