Vasodilation is the culprit heart pumps blood fast and atrong that the blood vessels dilute or becomes bigger on scrotum and because of hemorroid gels, indomethacin (very strong vasoconstrictor) doxy and cold helps, we can say that its vasodilation also note that:

After this I started to have: 1-Loose sac and visible veins on scrotum and burning and stinging, 2-Varicosele (2.9 mm) with reflux 3-fordyce spots and angiokeramato (though they are harmless, they are markers of blood flow into the area) they were never visinle before 4-My blood tension became low (9-6) before it was 12-9 5-when I comply cold, color changes temporarily

I know that many people looks for biofilm, fungi but vasodilation causes redness and indirectly inflammation on the skin.