Why have my knees been popping for five years?

For years my knees popping have woken up the dogs; that is how loud it is. The first week of this month, January, my right one began to feel like something is out of place and, with some of the pops, there is a pain . Is it arthritis or something else? Sometimes it hurts a little to walk on it when I get up then it quickly feels alright again.