Legs ache like mad! Bad circulation?

From when I was little I've always suffered from cramps in my legs, they were that bad that the cramp would last around 8 hours of even days. If it's not cramp then my legs always ache as if I've done a big work out. I presume it's bad circulation? I'm not a lazy person and have a very active job so it's not like I'm a couch potato. Does anyone know any supplements that I could take to help? I eat enough fruit and veg also.