Thank you.. I have the same problem.
Hi,
This could be an allergic reaction which is causing the itchiness and the pressure of your scratching is causing the bruising of the skin.Or simply dry skin which is causing it.
The allergen could perhaps the perfume you are wearing or some kind of cream/lotion.
Or it could be a reaction to any other substance in your environment.
Different people can tolerate different amounts of itching, and anyone's threshold of tolerance can be changed due to stress, emotions, and other factors. In general, itching is more severe if the skin is warm, and if there are few distractions. This is why people tend to notice itching more at night.
Apply a soothing lotion like Calamine.Avoid soaping the area till it sibsides since soaps dry the skin and can aggravate the symptoms.
ref:http://www.myonlinewellness.com/topic/topic100587035
The bruising will resolve on its own.If you notice it without your scratching it then you will have to get it evaluated.