What is causing welted red marks on my jugular vein?

Welted red marks on your jugular vein could be caused by various factors, including an allergic reaction, insect bites, or irritation from a tight necklace or clothing. Additionally, conditions like superficial thrombophlebitis or infections could contribute to the appearance of these marks. If the marks are persistent, painful, or accompanied by other symptoms, it's advisable to consult a healthcare professional for an accurate diagnosis and appropriate treatment.