Warts can be painful and very difficult to get rid of. They are caused by an infection of the Human Papilloma Virus (HPV) and there are literally hundreds of different types of warts. Often they are contracted by injury to exposed skin in public areas like bathrooms and pools.
Warts under the foot and on toes are often more painful as they are located on a weight-bearing surface and have a lot of pressure on them, making them hurt more. Treatment of warts on the feet can sometimes take a long time, as warts are quite resilient and often have their own blood supply, ensuring that they can continue to grow even in the worst conditions.
Your Podiatrist will be able to advise you of the best course of treatment for your wart. These can range from controlled acid treatments (which are mostly painless), to cryotherapy (freezing) of the lesions.