That happened to me too, but it was in one of my calves. I didn't even know my calf was swollen until my husband noticed it one day while giving a foot massage. Anyways, I thought I might have a clot, because leg clots (and poor leg circulation) run in my family. Doctors did an MRI and found no obstruction. His diagnosis: "veinous insufficiency." He said that the valves in our veins get worn out over time from pushing blood upward. As they wear, they don't close completely after pushing blood through, and allow some blood to seep back through, causing it to pool, and causing swelling in the leg. If you have a clot, you'll know because your skin temperature near the clot will be burning hot to the touch. This is a medical emergency if it happens.
I've had this swollen calf for three or four years now and have tried everything--elevation with pillows, inverted yoga poses, Western doctors, alternative therapies like cranial-sacral and Reiki, herbs, etc. It's still a great mystery to me and my doctors what the problem is. I suspect genetics--Mom has awful varicose veins, Dad had to wear compression stockings to help with circulation because he got so obese, and Grandmother always complained of dull and crampy legs. In my family, this problem seems to be a symptom of wear and tear. I am at my ideal weight (5'6'', 128 lb.), so the problem is not weight at all. It started in my mid- to late 30's, which seems to be when the leg vein weakness (and premature greying) kicks in in my family. When I wear tight socks, the band leaves a deep impression, and in really hot weather, the calf is prone to "pitting." It's not that noticeable really, but boy do I notice it! For example, I can see the muscle definition in one calf, but not the other. I am pretty much resigned now to pants and longer skirts, and I don't stand or sit for long periods of time. I take breaks from my desk, and put my lets up whenever possible.
I'm sorry this isn't much help. I feel for you. Swelling is usually caused by poor circulation of lymph or blood. If your problem is lymph, you might try find a cranial-sacral therapist who knows how to stimulate lymph circulation and clear blockages. This didn't work for me because my problem was blood, not lymph. But I know this has worked for others I know who have lymph blockages. Your doctor will tell you it's hooey, but it's not. It's worth a try.
Sincerely,
Manmohini