I have had these calluses since I was young. I am now 57, and they are getting very painful. I use a pumice stone every day and soak at least twice a week. The pain is a shooting pain from outside to the inside of the toe. I am on my feet a lot. My feet are also starting to have a creeping type of itch on the topside. Is that related?
It sounds like you have a corn that is pressing on the nerves in your big toes. Besides pumice stones there are over the counter treatments that can be used to dissolve them. There are also pads that you can put over them. Some people use Vasoline to lubricate the area and help break them up. Make sure that you're wearing foot friendly shoes that provide good cushioning and give your feet room to move.
If those things don't work you should see a foot doctor and see what he/she has to say. If they get too bad they can cause bursitis, an inflammation of the cushioning sacs in the feet. Corns can usually be treated quite successfully (without the need for surgery).
Health Central has a nice section on foot pain: http://www.healthcentral.com/chronic-pain/foot-pain-000061_8-145.html
Foot Pain – An Introduction
What Your Feet Say About Your Health
Foot Pain - Forefoot Pain
Hall of Shame: Shoes That Cause Pain