I hit a vein on my foot really hard and now it's bulging and getting really big. what is it, and should i be worried?

No: probably popped a vein and u should ice it and rest it

Trauma to veins: Trauma to veins can cause several problems including bleeding, swelling and discoloration around the injured area due to bleeding around the vein. Sometimes a vein injury will cause the valve in the vein to rupture leading to varicose vein formation or even to clotting of the vein. If you have a vein problem then see a vein specialist for a full venous evaluation.

Vein: Most likely result of trauma to area There is a homeopathic gel called arnica which will help reduce the inflammation and swelling Warm compress may also be beneficial If it doesn't resolve there may be bone injury and the vein is bulging due to the underlying issue May need an X-ray See a podiatrist or orthopedic surgeon