What can I do to manage pain from osteoarthritis? What medicine (or other means) works best to relieve severe pain from osteoarthritis?

Many things. Even though you have arthritis, you need to find a way to continue to exercise. Non-impact things are the best -- swimming, biking, etc. Depending on where the arthritis is can also tailor your treatment. Even just a little exercise each day makes a difference. Medicine includes tylenol (acetaminophen) and anti-inflammatories. Consult with your primary physician to make sure there are no interactions.