This has been reoccurring for 3 years or so. I can run, jump, etc....but I cannot kneel even on a soft surface. Today I had capris, and he slight friction from the pants to my knee cap as I got in my car was sudden and excruciating. It feels like a tendinitis or something? No noticeable swelling, but feels tender and somewhat soft in the area. The sensitivity comes in waves, maybe every 3 mins or so, goes away, then surfaces for no particular reason I can mention. Any ideas???