just see a doctor they will tell you if its a important vien or if its healing on its own. im 12 and it happend to me only in my arm after i was in a car accident luckly i walked away with only a broken arm and a few cuts and bruises. hope i helped! :)
-Rheanna
They usually heal by themselves, however the bigger issue is why did the vein rupture? I'm not sure what "busted a vein" means. There is usually a co-factor, which could be fragility of the vein or a problem with clotting factor? Is there continued leakage of blood into the tissue? If there is continued leakage the blood may coagulate and harden under the skin which might be a cosmetic issue. It wouldn't a bad idea to have an M.D. take a look.