I have something that looks like a callus on the inside of my small toe. it is very painful and sometimes makes it difficult to walk. how to treat it?

See below: It is not feasible to be sure without examining the lesion, it may be a corn or a wart. Try over the counter treatment for a corn and see if that helps. You may need to make adjustment in your foot wear to reduce the strain on the skin of the affected area.

Shave the Bone.: There is only a couple of things it can be. A wart, which is least likely, based on your description. The most likely is a callous that is produced from the 4th and 5th toes rubbing together over prolonged periods of time. The little sharp edged bones trap the toe skin and cause localized tissue damage. The protective mechanism is the callous. Use a separator between the toes or toe surgery.