My bones are always cracking and I'm only 18 years old..?

If I twirl my wrists around they crack constantly and whenever I bend down my knees and ankles crack and like my ankles and knees and stuff will get really stiff so i'll crack them and they'll feel better and just whenever i move my ankles around a certain way they'll crack.. i'm lacktose intolerant so i don't get as much calcium as i should but i'm only 18 and i don't understand why my bones are so stiff and crack all the time.. i don't wanna do any permanent damage but it's very hard to avoid, it's not just the cracking of the knuckles every once in a while it's like everywhere and i can't stop or else i get really stiff and uncomfortable.. can someone help me out? thanks.