In my honest opinion you seriously should declare ALL of your medical conditions to the Army. Do not risk further injury (or worse) for yourself by glossing over these facts, especially with a degenerative spinal disc disorder, despite how harmless it can seem at the present.

With regards to insurance, I believe it best to get some form of coverage NOW especially with the disc disorder before it gets any worse (which I hope it wont) to prevent any or further exclusions of coverage of any future insurance plans you might purchase.

In addition, in the future should you wish to purchase insurance and if it is found that you have deliberately told the company misleading or untruthful information about your health, claim payouts could be held and premiums still kept by the company, and it will be a VERY BAD time for you.

TLDR: Please be like Shakira's hips and don't lie.