Should I be worried about a lump on my dog's left hind leg?

My little 3 year old Chihuahua and Miniture Pinscher has a lump about the size of a number two pencil's eraser and I don't know if I should be worried or not. I know this is dumb, but I haven't taken her to the vet yet because I wanted to see if there was anyway it would wear off or if there were any old remedies. It's been about two weeks since I found out. Please help me (and don't say things like "Go to the vet, already!", or "Are you blind? Take your dog to the vet, you retard,"). I think I may have missed some details so be sure to point them out for me. Really need your help.