Thanks for query,
Due to constant driving you get collection of blood within calf muscle as it has no gravity to back to heart.
This happens when you are on traveling due to lesser movements of leg,inadequate of drinking water or fluids leads to stagnation of blood in veins as it tense it causes you swelling & pain.It some times resulted in Deep vein thrombosis
You should elevate your leg for at least 4-6 hours.
Take enough water. If you have any changes in color of your skin of leg or any more swelling consult your doctor.
Squeezing of the leg should be strictly avoided as some times it may cause embolism