Advice Regarding Cervical Osteoarthritis

Several months ago I was diagnosed as having cervical osteoarthritis. The first time I suspected it, was about 7 years ago. I was on vacation when I developed excruciating pain in my neck which radiated down my right arm causing numbness. Fortunately, I was able to go to a branch office of my HMO in another state. The doctor said it was cervical osteoarthritis and it was causing a pinched nerve. I had been taking NSAIDs such as advil and aleve and neither helped with the pain. I was given a small prescription for a painkiller but only needed to take it for 2 nights as the pain subsided. When I went home and told my regular doctor what happened, she said I couldn't get a definitive diagnosis unless I was xrayed while in pain. So for the longest time I went without any neck pain until several months ago. This time I got xrayed and was told it was cervical osteoarthritis. I was sent for physical therapy for 4 sessions. It amounted to getting my neck stretched for 20 minutes at a time. Since then, I've been taking Osteo Bi-Flex triple strength twice a day. I have 3 questions-- (1) What causes flare-ups of neck pain and can it be prevented? (2) Anyway to tell when it's about to flare up? (3) Osteo Bi-Flex is touted as building up cartilage--does it work only on knees or is it good for osteoarthritis anywhere?