My first thought and question would be....are you Diabetic? If so you could be suffering from Diabetic Neuropathy. My husband has a lot of burning in the balls of his feet because of this.
Here is a short description of it and a link with more info.
The areas of the body most commonly affected by diabetic peripheral neuropathy are the feet and legs. Nerve damage in the feet can result in a loss of foot sensation, increasing your risk of foot problems. Injuries and sores on the feet may go unrecognized due to lack of sensation. Therefore, you should practice proper skin and foot care. Rarely, other areas of the body such as the arms, abdomen, and back may be affected.
Symptoms of diabetic peripheral neuropathy may include:
* Numbness (severe or long-term numbness can become permanent)
* Burning (especially in the evening)
In most cases, early symptoms of diabetic peripheral neuropathy will become less when blood sugar is under control. Medications can be taken to help control the discomfort if needed.
I hope this can help, I am sure there are more reasons to the burning, but this one is the first to come to mind for me. Like I said, only because of my knowledge of Diabetes.