Callosities, also called corns, develop on areas of friction and pressure. The shape is roughly conical, with the pointed end in the tissue, digging in and causing pain while walking. These callosities are difficult to treat.
If you cannot visit a surgeon, try the following:
First, change your footwear, so that there is no pressure on the points where the callosities are. You may need to have your shoes specially designed.
Second, try applying corn-caps. These soften the corns, decreasing the pain.
Third, shave off part of the corn yourself. The shaving process will be painless, since the callosity is made of non-living tissue. Keep shaving till you reach sensitive tissue. You may end up drawing a drop or two of blood. After shaving, the pain usually disappears, since the callous becomes too small to transmit pressure. (Be sure to wash the foot thoroughly and clean with an antiseptic before and after shaving it.)