Brief Answer:
Impaired circulation can cause pain, discomfort and discoloration.

Detailed Answer:
Hello dear, welcome to Ask a doctor's service.
I read your query and here is my advice.

You can attach a photo of the legs on reports for me in order that I can see their situation.
The pain and change in color may signify impairment circulation on the legs.
Suffering from varicose veins, diabetes or hypertension may cause impaired blood circulation on the legs causing you to have pain, discomfort and discoloration.



Hope I have answered the question.
Let me know if I can assist you further.

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Brief Answer:
Vasodilation mainly caused by exercising or heat exposure.

Detailed Answer:
Hello dear and thank you for asking again.
I finally can see the photos you attached and I can see the rash you are having.
It seems like vasodilation rash on skin of your legs. It can be caused by excess exercising or exposed to sun or exercising in hot weather .
It doesn't seem much important and can't signify a disease.
Having rest and drinking more water and fluids is needed.
Stop staying in hot environment or under sun exposure.
Let me know if I can assist you further.

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