The heat can be harmful for feet because it causes swelling. Particularly if you are sitting or traveling for a long time, problems like this are almost expected.
If you want to stop this problem, than you should shower your calves with cold water, and also avoid crossing your legs. You can try to minimize sitting or standing for too long.
Another thing you can do is to prepare a natural beverage. Chop a parsley root or leaf and pour it with 4 ml water. Caver and leave it to stand overnight. Strain in the morning, add the lemon juice and drink. You will have to drink 1 dl, three times daily.
Also you can try another recipe. Add four tablespoons of flax seed in one liter of water. Cook for about 15 minutes. Cover the hob and leave it on a warm place for an hour. Then add the lemon juice. Drink one glass on every 30 minutes, until you drink the whole measure. Keep it drinking for the next 10 days.