Suggest Remedy For Reddish Bumps On The Back Of Knees

I noticed bumps on the back of both of my knees a few days ago. Since then, more have appeared. They are larger in the crease and they are red, the surrounding bumps are just skin colored and smaller. I haven t experienced any itching or discomfort yet. Should I be concerned? Do you know what could have possibly caused this, and how to get rid of it?