What can be causing my severe knee pain?

[mike4602]

I began running over a year ago as means of loosing weight. Just recently, (about 2-3 months ago) I started noticing pain on both of my knees a few hours after my run. There has been times when I couldn't get out of bed because I felt too weak to stand. I have stopped running because it hurts pretty bad. Pain usually goes away with ibuprofen and rest. I am just not sure what can be causing this because I have not experienced any fall or injuries to my knees in the past.