They are most likely a condition called pitted keratolysis. It is an infection by a bacteria (a Corynebacterium) in feet that sweat a lot. As sweat accumulate and is not allowed to evaporate it creates an environment that the bacteria like to grow in. All the multiple tiny holes or pits or craters come about because of an enzyme that the bacteria release to eat away at the keratin in the outer skin layer. The skin also tends to have a whitish colour which is due to the accumulation of moisture in the skin. The feet also commonly have a foul odor as well due to the bacteria causing sulfur to be released.
There are two approaches to get rid of pitted keratolysis: first there is to use a topical antibiotic that can usually quickly and easily deal with the infection. The second and more important is to get rid of the environment that the bacteria likes to grow in, so the pitted keratolysis can not longer be a problem. This means good foot hygiene habits. The feet need to be washed, cleaned and thoroughly dried every day. Go barefoot as much as possible so that the sweat can evaporate and the feet dry out. Wear socks and shoes that can help absorb moisture or at least wick it away from the foot. Change the socks during the day so they can help keep the feet dry. An absorbent powder in the socks can also help. Odour eating insoles can also help absorb moisture.
If you have pitted keratolysis and none of these measures are helping, then please call us and come in for a consultation and we can advise more clearly on what needs to be done.