My knees hurt, but in a strange way?!

3 weeks ago I stood on my knees for about 20 minutes trying to fix my computer (i should have sat in the chair) and the next day my knees burn!. It has been 3 weeks and still the same!. They ONLY time it burns when i'm on my knees then i try to get back up and as i get back up my knees BARELY scrape the carpet and it burns really bad---feels exactly like a carpet burn, but my knees only scrape the carpet ONCE!. I look at my knees and they look perfectly normal and I can run, walk whatever and not feel anything!. I tried putting lotions and such but it is still the same!. I'm in my early 20's at don't have problems!.
what can this be!?Www@Answer-Health@Com

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