Know that I am not a doctor. I am simply researching your question and reporting my findings to you.
My strong recommendation is for you to schedule an appointment with the doctor right now.
Do you have any other symptoms?
Since you have pain, it has been going on for over a week, and the change in color to purple...these are all strong indications that you need to see the doctor.
Here is some information from Medline Plus about skin rashes. I am concerned about some things I am reading that the purple color can indicate bleeding under the skin.
Here are some questions they may ask you...these came from the Medline Plus article:
* When did the rash begin?
* What parts of your body are affected?
* Does anything make the rash better? Worse?
* Have you used any new soaps, detergents, lotions, or cosmetics recently?
* Have you been in any wooded areas recently?
* Have you had any change in your medications?
* Have you noticed a tick or insect bite?
* Have you eaten anything unusual of late?
* Do you have any other symptoms like itching or scaling?
* What are your underlying medical problems? Do you have, for example, asthma or allergies?
Go call your doctor right now. I hope it turns out to be nothing serious. Let us know what happens if you can.