I find any product that contains Cocoa butter and (like Shelley said) Vitamin E helps reduce scarring. It's reasonably cheap, most of the time, and there's often a large variety of products that you can try out. (Well, there is where I'm from anyway).
Most scars disappear on their own with time, depending on the size and how deep they are.
Your BCG injection was in your arm right? You could probably cover it with clothing as well, and no-one will know it's there.
Hope that helps, even if this post is a bit late.