I often read this forum over the last few months but have nerver felt the need to post anything until now. I'm only a teenager but I know what you mean by this. I can crack just about everything in my body, it started with my ankles but that's just happened where as other joints where more 'self inflicted.' I know how unconfoable this can be my I can still can crack ankles but don't need to they just feel the same as they did before. I got this this when I was in primary school about age 10 or 11. I got physiotherapy for it and got some shoe foam inserts cleared it up quite quickly from what I remember. This at least from my exprieance isn't a permanent thing.
Hope that's reassuring and maybe something to look into.
Andrew