Hi, I have a squishy soft lump on my left shin in between the kneecap and my ankle of course. When I perform calf raises, it pops out but I restrain from any acitvity that doesn t flex it, it does not show itself. In fact, when I am lying down and I raise my leg all the way up, it is totally gone and it feels empty (dent like) at the spot...what is this? Please, please, please answer!