There are a number of conditions that could cause itchy bumps and lumps on the bottom of your foot. One of the most common is tinea pedis, or athlete's foot. This is caused by a fungus. It appears as pink scaling patches, bumps, and sometimes pink blisters.

Another condition that could cause itchy bumps is dyshidrotic eczema, a type of recurrent dermatitis of unknown cause that results in tiny blisters (vesicles) that itch or burn.

Another cause of itchy feet is contact dermatitis, where itchy lumps and fluid-filled blisters may erupt when feet come in contact with something that causes skin irritation or a localized allergic reaction.

These are only some of many potential causes of itchy lumps and bumps on the feet. Treatment differs depending upon the diagnosis. It is therefore important to be examined by your doctor for correct diagnosis and treatment.