Nose Hoop

I've had my nose pierced for about 2 and a half years now and I always wore the little diamond/bone piercings, I recently changed to a hoop and its been a little sore. I don't know what gauge or size the new hoop is but it fits into my piercing pretty well, I'm just worried that it might get infected or something like that. No green or yellow discharge just a little redness and tiny soreness. Maybe because I've been playing with it? Thanks! :)