I started with one wart on the ball of my foot a few years ago. But it has started to multiply, and now I have about 7 on my foot. I decided to take action and have been putting a wart removal solution (sasilic acid.) I have also been putting duct tape on it. Its getting white all around the warts. Is this what should be happening. How long do you think it will take to get rid of it, and how will I know when it is finally dead?