Well many people experience severe irritation, itching or pain in body specially legs when they start walk or running / jogging after a long period of time. The main causes of this are:
1. The body is not used to the feeling / vibration, as if the person started the exercise after a long rest.
2. the muscles are stretching and as body is not accustomed to this feeling, so it takes it as itch or pain.
3. Pores are opening, as we start exercise, the pores start opening.
4. Lack of water.
5. High intake of salts.
6. long bath with hot water, makes your skin dry, causing more itch.
To see solution to how to solve this problem, see this page: http://health.nabtron.com/issues-of-starting-running-after-long-time/6/