Cause of itching skin total area from the left knee to the ankle with no visable bumps or rash.?

One does not have: To see something to itch...For example (not implying this is what you have) if one ever works with insulation and doesn't wear proper clothing they get fiberglass on their skin - it itches intensely but one doesn't see anything....You can try showering and applying soap and water to the region and then applying an over the counter Hydrocortisone cream. If no improvement see a dermatologist.