I need to know why my body produced blood clots. My foot, ankle, lower legs swel!

I need to know why my body produced blood clots. My foot, ankle, lower legs swells if I walk around the block.

The first simpton's started about two years, with pain. It would ache, then it felt like it was going to sleep, with the tingling needles. Recently, two months ago, my foot & lower leg would go to sleep, then go completely cold & numb. About the same time my leg from the knee down, would swell up. Two weeks ago, surgens removed blood clots from up and down the same leg, also in my lower abdomn, but couldn't tell me what caused them, or what might have caused the swelling to start with. Now I can't stand upright for long, one minute down and it starts to swell. I'm over 50 and enjoyed physical activities all my life, walked everywhere, worked physical jobs, weight is good. I quit smoking, but there has to be something more that is causing this problem, thanks for any ideas, I'll read all.

Have you had your blood tested to see if you have a clotting disorder? Ask about thrombophilia.
Blood clotting factor 5 is a common one (my sister has this and had to take blood thinner shots twice a day throughout her pregnancy just to be able to carry a baby to full term).

I forgot to also mention to ask about Lymphoma. My mom has Non-Hodgekin's Lymphoma and developed a blood clot in her leg that went to her lungs from an enlarged lymph node that slowed the blood circulation down enough in her leg to cause a clot. People have lymph nodes all over their body (including abdomen).