No you can use a pain code with the external cause code. It doe s not need to be a injury per se. Maybe the only consequence of the external cause is pain.
I am saying it could happen, you could have neck pain and the providers states it is due to an MVA. There may not be any external symptoms nor is the provider saying whiplash just acute neck pain associated with an MVA.
The M chapter has a note that if applicable you are to add the external cause code. It would be applicable if the provider documented it.