Has anything changed recently? Dietary, amount of exercise, even alcohol intake? It seems that a sudden onset of leg cramps without any change in your routine is unusual. Are you putting longer hours in at the bike shop than usual? The kind of shoes you wear during the day and the kind of pad you stand on can make a huge difference. If you're working as a mechanic and at a bench it's sometimes useful to have a stool available to sit on for a variety of positions so that you're not standing all day.