Knee pain/discomfort question

About 3 days ago I noticed my left knee was a little sore; it almost feels like it needs to “pop”, and I feel the discomfort on the top of my knee. If I bend it or walk down stairs that is when I notice the most discomfort. The only thing I’ve been doing different is the elliptical; I am on my 6th week of using it at least 5x a week. I haven’t used it the last few days in the hopes my knee discomfort would go away, but no luck yet.

Has this happened to anyone else? Is this something that will clear up on its own with proper stretching and icing? I really don’t want to go to the doctor bc like I said I didn’t really “do” anything to cause this.