Sensations felt during meditation and transmutation such as the ones you have described are very normal. The best thing to do is to not become identified with them. Sometimes we may have sensations, and other times, not. They should not be seen as a direct indicator of someone advancing or not. You can investigate them in meditation, but do not become attached to sensations. There are countless reasons why we may have a sensation, but advancement on the path requires psychological and emotional development.