I have very prominent veins on the top of my foot, can feel it throbbing and struggle to put any weight on my foot.

Get Evaluated by Doc: This must be evaluated by a vascular surgeon. The first step is differentiating between a superficial artery and a vein. If it is a vein, it may have become inflamed, a condition known as superficial thrombophlebitis. A full venous ultrasound would be warranted to rule out deeper clots and if that is negative, warm soaks, nsaid's, possibly antibiotics and ace wraps may be appropriate.

Venous Insufficiency: You may be suffering from a condition known as venous insufficiency, in which some of the vein valves in your leg or foot fail, leading to bulging prominent blue veins under high pressure forming just beneath the skin. This condition can lead to pain, throbbing, itching swelling. You may also be developing varicose veins as a result. I would recommend a venous reflux ultrasound.

Vein problem?: I agree with dr. Gotvald, you could have varicose veins. However, prominent veins on the tops of feet are common and may be entirely normal. Throbbing pain frequently occurs but having trouble putting weight on your foot because of veins doesn't happen very frequently, in my experience. I agree that a venous ultrasound will be helpful but there may be more going on than just vein trouble.

Foot veins.: Many patients complain about foot veins and their treatment is usually cosmetic. Throbbing foot veins are usually the result of transmitted pulsations from the underlying arteries. These veins can be treated by usually sclerotherapy or removal through micro incisions. See a vein specialist.