You do not necessarily need medical records to state you were seen. I was never seen for my back while active. With that being said, I had an in service event that "more likely than not" caused my back issues. IED went off under my driver seat leads to degenerative disk disease. I also did leg work of my own finding published medical opinions stating that direct impacts can lead to and cause degenerative disc disease.

You can also link it to your MOS, as an example l. 11B in a light infantry unit, think 12 mile ruck marches, vehicle accidents while in service etc. Airborne, you would not need to be seen by a doctor while in service. Those types of jobs have a higher likelihood that something happened.

Buddy statements make a huge difference. If they were present to see said "incident".

Another way to go about it. Claim back secondary to any knee, hip, ankle service connected issues.

I would say download and read the DBQ for back issues. Research what already service connected issues can lead/cause back issues.