What Causes Inflamed Skin On Scrotum?

At random times, every couple of week or months, the skin on my scrotum feels inflamed. No pain to the touch but more of burning feeling upon examination theskin is darker, but what I see is, many,many tiny, 1/8th inch to pin head dark spots which when touched or pressed will disapear back into the scroutm It seems as if they are tiny blood ??? bubbles.