It is a common condition for runners to see their skin turn white on the soles of their feet. The soft skin, dotted with little holes, can smell horrible but soon disappears after the skin has time to dry, only to return after the next run. If left untreated, the condition gets worse and then turns into a rank-looking skin, akin to Swiss cheese, a sponge or the surface of the moon as the little holes turn into crater-looking things.
Well, what you have is pitted keratolysis. It is a bacterial infection caused by damp, warm conditions. It is common on the feet because they are stuck in shoes and socks, so sweat cannot evaporate. The hot, sweaty foot is the perfect condition for this bacteria to flourish, but is easy to get rid of.
Go to your doctor and they will prescribe antibiotics. They will probably give you oral and cream antibiotics. Because not much blood gets to the thick skin of the soles of your feet, it is imperative you are strict with taking and applying both. This way the bacteria is completely killed. Otherwise, the condition will return soon after you stop your oral treatment.
Avoid cotton socks like the plague. They adsorb and hold sweat. Buy woollen socks, or bamboo sports socks, as they wick away sweat.
If you have pitted keratolysis, then take an extra pair of socks to work and change them midday to help get rid of the condition. Maybe even take an extra pair on your runs so you can change mid-training. Good shoe and sock practice will go a long way to preventing, as well as healing, your pitted keratolysis.
Wear shoes that are breathable too, like sports trainers. And, if you can, do not wear shoes at all so your skin can breath. Have a pair of flip flops on hand at training, so you can get your feet back in the air as soon as you finish running, instead of travelling home in the sweaty socks.
If you have particularly sweaty feet, have two pairs of shoes so you are never putting wet shoes back on. Over night, leave them near a dehumidifier.
Wash your feet with soap. As soon as your arrive home, take off your shoes and wash your feet. If you are able, wash your feet during the day before putting on a new pair of socks. But when you wash your feet, make sure you dry them thoroughly. Wet feet will cause the condition, whether the moisture is from sweat or normal water.