In which case whats the big deal in letting everyone know what is the exact injury, all very vague and dismissive makes me suspicious - maybe just me.
Backs are a complete mystery to Doctors.
They can only correctly diagnose in about 25%-30% of cases, usually when something shows up on a scan (herniated discs for instance).
So assuming the scans show nothing, they have at most a 30% chance of a correct diagnosis, which might climb if they are sending him to the best specialists.
I had all this from my GP a few years back, when I was frustrated they couldn't give me a proper diagnosis.
What eventually fixed it? Time, rest, and not had a problem since.
Just one of those things, nothing to be suspicious about.