What Causes Severe Itching On The Body Particularly In The Evening?

For a few weeks now I have experienced very strong itching, this happens mostly in the evenings. During the night I often scratch to the blood, I have bought some lotion for very dry skin which soothes the skin momentarily but not completely. Recently I have noticed small purple spots that look like bruises on my thighs, a place where the itching is very intense.