Good that your son was immediately attended by emergency medical service.
How old is he? If you still change diaper I suppose he is too small to even speak of his complaints.
In case he has headache he would cry . As he is not having any vomiting
or fluid from ear/ nose , that's good. Also if there is an internal injury he would have been drowsy.
Just that he is not eating as before does not mean anything. He might be having slight pain and discomfort for which he is holding his head to the left. The reason for squishy may be soft tissue injury
. Worry if you notice notice any discolouration or bruising and palpable bogginess behind the ear as it indicates underlying injury.
Anyways in case you observe any symptoms just get the investigation done:
1. X-Ray skull ( AP and lateral )
2. CT scan
brain plain ( in case you make sure he remains still during the procedure ).