At your stage little can be done, I was lucky that mine was caught early in my 20s and was do to all the stress I put from leading a non-active lifestyle.
As of right now, fusion and possibly physical therapy. Disc degeneration is a big mystery. People don't know why it happens to some and not others. I have degeneration in nearly the same place C4-5-6.
You can still be active, but you can't turn your neck. You can ride bikes, walk, and do many things.
I'm only 26 but due to damage from years of just not taking care of myself...I was told by a doctor to never RUN, ever again. I honestly cried for three hours. I love running, being hyperactive, whipping my neck around for humorous effect...hell I can't wait until I can finally have sex without worrying if my back will give out.
What pisses me off is that even with all my physical activity and therapy, science has no solution for this.
Stay hard pills...why not
Baldness treatments...ok
Having a shitty back with a full head of hair and a willing erection? Methinks these drug companies haven't thought their brilliant plan all the way through.
Thing is...you may be hosed by this...but you still have your mind, and you're not dying. It's going to be painful...REAL painful, but fusion will take it away, and until they can inject cells to regrow your cartilage, we have to make due.
J- Hopes to run a marathon in his 40s if they come up with a treatment by then.