I saw different doctors about the pain at the bottom of my feet and was told I have a bunion on left foot. I have used different inserts in my shoes, but they never helped me. I suffer when standing in one place, and the only way I feel a relief is by using shoes with a very small heel, but even that is only for a short time. I've tried exercise, massaging my feet, and walking for a short distance.
What can I do to at least last longer on my feet without pain?
You didn't say what kind of doctors you've seen. If you haven't already tried them, I'd suggest seeing a podiatrist or an orthapaedic specialist. You may need a specially designed orthotic to relieve the pain caused by your particular problems. In the meantime, here's a link to an article about foot pain that includes a chart listing the different causes of foot pain and the recommended footwear to help minimize discomfort:
Foot Pain - Introduction
Here are some other links that might be helpful, too:
What Your Feet Say About Your Health
Why Yoga May Help Soothe Chronic Pain