Recently, for the past few weeks. Sometimes when I stand up from sitting, my left knee and sometimes my right, feel weird and need a cracking. I either shake them or bend them towards the other knee and it cracks. It feels rather good and reliving when I do so. Knees doesn't hurt in any way possible, but I find this cracking thing odd... I am in very good shape, I run on an average of 5-7 miles per day and I am 18 and a male. Please help. I'm I growing? Will this cracking thing stop soon? Thank you