There Is A Red, Swollen, Painful Area Just Below Of My Knee. Is It Tumor ?

Hello, My name is Brad. I m five feet, ten inches tall, and i m 56. Throughout my life, my weight has always been around 155, i ve never had hypertension , always had normal cholesterol, i ve never smoked nor consumed liquor, I never had diabetes , and I have a history of cellulitis affecting various parts of my anatomy . On my right leg, just below the knee , in between the front and left of the leg, there is a red, swollen, painful area that seems firm-hard when touching it. It just started revealing itself recently. I don t recall bumping it or twisting that area. I m aware of P.A.D. and have been doing some reading about it. Maybe it s a tumor, a blood clot, or something less sinister. Thank you very much. Good bye.