What Causes Cramps And Stiffness In The Calf Muscles Of Both The Legs?

Was walking in Disneyland last Thursday and just had severe cramps in the calves of both of my legs. The rest of the day had to sit as much as I could while my family enjoyed the park. Could barely walk to the car to leave. Tried walking as little as possible the rest of the trip. Thought I just needed to stay off of them and get a good nights rest. This morning still stiff and painful. Have never had any problem like this and can t figure out why it came on so fast.