You probably built up muscle from running all the time, so even though you may be losing fat it doesn't show up on the scales as a loss because heavier muscle mass has replaced the fatty tissue. Try measuring your waist, arms, thighs, etc instead of weighing yourself, but only once a week/fortnight, or track your bodyfat percentage. Another thing is if you're already a low-normal weight for your height (there's no data on your profile so I don't know) then you may already be at your body's preferred natural weight and will find it extremely hard to get any lighter. In that case, it's better to just focus on being healthy and fit.
Continue to stick to your diet and exercise routine and eventually u the scale will start to move.