Hello, thank you for sharing your problem with HCM.
I think there is some problem in your Temporomandibular joint (joint of the jaw) because it can be possible that at the time of falling you got a direct hit on it.
The joint lies in front of the ear that is why you are feeling pain and unable to open mouth.
You should visit your dentist
to get an x - ray
done of the joints and get the problem diagnosed.