What exactly did you do Neale?
There seems to be a commmon thread here: minor accident = shoulder injury! I've got a permanent grade 3 separation now after a spill last year. Looks weird as hell, but I've got full use of the limb. It still aches from time to time, but no big deal.
I wear an EVS brace on it when I ride now.
I could've had surgery but decided not to for a number of reasons.
My chiropractor didn't say to quit riding, I just had to stay off dirt bikes for a while until it healed. I kept riding my road bike though, even to the appointments, which he found amusing!
It sounds like your injury is much more serious than mine though. Like VMX247 says, maybe a second opinion is required before you make a major change to your life.
Good luck!
Tex