Most arthritis is due to some type of trauma (unless it is an autoimmune type). Any time you injure your body arthritis can develop in that area.
Fibromyalgia can develop due to any form of traumatic injury (physical/emotional)...at least that is the theory. They really do not know what causes it.
A herniated disk can certainly cause all types of pain. You are dealing with back pain, walking pain, the adaption of your body (legs, back, stride) to compensate for this pain.
The balance, overshooting with your step, is something I can totally relate to (as I have that problem as well). I believe your physician is unsympathetic to your needs and you may do well to seek out someone who is more understanding.
Best of luck to you.